ON SOME MARVELS IN TELEGRAPHY.

Within the last few years Electric Telegraphy has received some developments which seem wonderful even by comparison with those other wonders which had before been achieved by this method of communication. In reality, all the marvels¹ of electric telegraphy are involved, so to speak, in the great marvel² of electricity itself, a phenomenon as yet utterly³ beyond the interpretation⁴ of physicists⁵, though not more so than its fellow marvels, light and heat. We may, indeed, draw a comparison between some of the most wonderful results which have recently been achieved by the study of heat and light and those effected in the application of electricity to telegraphy. It is as startling to those unfamiliar⁶ with the characteristics of light, or rather with certain peculiarities⁷ resulting from these characteristics, to be told that an astronomer⁹ can tell whether there is water in the air of Mars or Venus, or iron vapour in the atmosphere of Aldebaran or Betelgeux, as it is to those unfamiliar with the characteristics of electricity, or with the results obtained in consequence of these characteristics, to be told that a written message can be copied by telegraph, a map or diagram reproduced, or, most wonderful of all, a musical air correctly repeated, or a verbal message made verbally audible. Telegraphic marvels such as these bear to the original233 marvel of mere¹¹ telegraphic communication, somewhat the same relation which the marvels of spectroscopic analysis as applied¹² to the celestial¹³ orbs¹⁴ bear to that older marvel, the telescopic scrutiny¹⁵ of those bodies. In each case, also, there lies at the back of all these marvels a greater marvel yet—electricity in the one case, light in the other.

I propose in this essay to sketch¹⁶ the principles on which some of the more recent wonders of telegraphic communication depend. I do not intend to describe at any length the actual details or construction of the various instruments employed. Precisely¹⁷ as the principles of spectroscopic analysis can be made clear to the general reader without the examination of the peculiarities of spectroscopic instruments, so can the methods and principles of telegraphic communication be understood without examining instrumental details. In fact, it may be questioned whether general explanations are not in such cases more useful than more detailed¹⁸ ones, seeing that these must of necessity be insufficient¹⁹ for a student who requires to know the subject practically in all its details, while they deter²⁰ the general reader by technicalities in which he cannot be expected to take any interest. If it be asked, whether I myself, who undertake to explain the principles of certain methods of telegraphic communication, have examined practically the actual instrumental working of these methods, I answer frankly²¹ that I have not done so. As some sort of proof, however, that without such practical familiarity with working details the principles of the construction of instruments may be thoroughly²² understood, I may remind the reader (see p. 96) that the first spectroscopic battery I ever looked through—one in which the dispersive²³ power before obtained in such instruments had been practically doubled—was of my own invention, constructed (with a slight mechanical modification) by Mr. Browning, and applied at once successfully to the study of the sun by Mr. Huggins, in whose observatory²⁴ I saw through this instrument the solar spectrum²⁵ extended to a length which, could it all have been seen at once, would have234 equalled many feet.27 On the other hand, it is possible to have a considerable practical experience of scientific instruments without sound knowledge of the principles of their construction; insomuch that instances have been known in which men who have effected important discoveries by the use of some scientific instrument, have afterwards obtained their first clear conception of the principles of its construction from a popular description.

It may be well to consider, though briefly²⁶, some of the methods of communication which were employed before the electric telegraph was invented. Some of the methods of electric telegraphy have their antitypes, so to speak, in methods of telegraphy used ages before the application of electricity. The earliest employment of telegraphy was probably in signalling the approach of invading armies by beacon²⁷ fires. The use of this method must have been well known in the time of Jeremiah, since he warns the Benjamites “to set up a sign of fire in Beth-haccerem,” because “evil appeareth out of the north and great destruction.” Later, instead of the simple beacon fire, combinations were used. Thus, by an Act of the Scottish Parliament in 1455, the blazing of one bale indicated the probable approach of the English, two bales that they were coming indeed, and four bales blazing beside each other that they were in great force. The smoke of beacon fires served as signals by day, but not so effectively, except under very favourable²⁸ atmospheric²⁹ conditions.

Torches held in the hand, waved, depressed³⁰, and so forth³¹, were anciently used in military signalling at night; while in the day-time boards of various figures in different positions indicated either different messages or different letters, as might be pre-arranged.

Hooke communicated to the Royal Society in 1684 a paper describing a method of “communicating one’s mind235 at great distances.” The letters were represented by various combinations of straight lines, which might be agreed upon previously³³ if secrecy³⁴ were desired, otherwise the same forms might represent constantly the same letters. With four straight planks³⁵ any letter of this alphabet could be formed as wanted, and being then run out on a framework (resembling a gallows³⁶ in Hooke’s picture), could be seen from a distant station. Two curved beams, combined in various ways, served for arbitrary signals.

Chappe, in 1793, devised an improvement on this in what was called the T telegraph. An upright post supported a cross-bar (the top of the T), at each end of which were the short dependent beams, making the figure a complete Roman capital T. The horizontal bar as first used could be worked by ropes within the telegraph-house, so as to be inclined either to right or left. It thus had three positions. Each dependent beam could be worked (also from within the house) so as to turn upwards³⁷, horizontally, or downwards³⁸ (regarding the top bar of the T as horizontal), thus having also three positions. It is easily seen that, since each position of one short beam could be combined with each position of the other, the two together would present three times three arrangements, or nine in all; and as these nine could be given with the cross-bar in any one of its three positions, there were in all twenty-seven possible positions. M. Chappe used an alphabet of only sixteen letters, so that all messages could readily be communicated by this telegraph. For shorter distances, indeed, and in all later uses of Chappe’s telegraph, the short beams could be used in intermediate positions, by which 256 different signals could be formed. Such telegraphs were employed on a line beginning at the Louvre and proceeding³⁹ by Montmartre to Lisle, by which communications were conveyed from the Committee of Public Welfare to the armies in the Low Countries. Telescopes were used at each station. Barrère stated, in an address to the Convention on August 17, 1794, that the news of the recapture of Lisle had been sent by236 this line of communication to Paris in one hour after the French troops had entered that city. Thus the message was conveyed at the rate of more than 120 miles per hour.

Various other devices were suggested and employed during the first half of the present century. The semaphores still used in railway signalling illustrate⁴⁰ the general form which most of these methods assumed. An upright, with two arms, each capable of assuming six distinct positions (excluding the upright position), would give forty-eight different signals; thus each would give six signals alone, or twelve for the pair, and each of the six signals of one combined with each of the six signals of the other, would give thirty-six signals, making forty-eight in all. This number suffices to express the letters of the alphabet (twenty-five only are needed), the Arabic numerals, and thirteen arbitrary signals.

The progress of improvement in such methods of signalling promised to be rapid, before the invention of the electric telegraph, or rather, before it was shown how the principle of the electric telegraph could be put practically into operation. We have seen that they were capable of transmitting messages with considerable rapidity, more than twice as fast as we could now send a written message by express train. But they were rough and imperfect. They were all, also, exposed to one serious defect. In thick weather they became useless. Sometimes, at the very time when it was most important that messages should be quickly transmitted, fog interrupted the signalling. Sir J. Barrow relates that during the Peninsular War grave anxiety was occasioned for several hours by the interruption of a message from Plymouth, really intended to convey news of a victory. The words transmitted were, “Wellington defeated;” the message of which these words formed the beginning was: “Wellington defeated the French at,” etc. As Barrow remarks, if the message had run, “French defeated at,” etc., the interruption of the message would have been of less consequence.

237 Although the employment of electricity as a means of communicating at a distance was suggested before the end of the last century, in fact, so far back as 1774, the idea has only been worked out during the last forty-two years. It is curious indeed to note that until the middle of the present century the word “telegraph,” which is now always understood as equivalent to electric telegraph, unless the contrary is expressed, was commonly understood to refer to semaphore signalling,28 unless the word “electric” were added.

The general principle underlying⁴¹ all systems of telegraphic communication by electricity is very commonly misunderstood. The idea seems to prevail that electricity can be sent out along a wire to any place where some suitable arrangement has been made to receive it. In one sense this is correct. But the fact that the electricity has to make a circuit, returning to the place from which it is transmitted, seems not generally understood. Yet, unless this is understood, the principle, even the possibility, of electric communication is not recognized.

Let us, at the outset, clearly understand the nature of electric communication.

In a variety of ways, a certain property called electricity can be excited in all bodies, but more readily in some than in others. This property presents itself in two forms, which are called positive and negative electricity, words which we may conveniently use, but which must not be regarded as representing any real knowledge of the distinction between these two kinds of electricity. In fact, let it be remembered throughout, that we do not in the least know what electricity238 is; we only know certain of the phenomena⁴² which it produces. Any body which has become charged with electricity, either positive or negative, will part with its charge to bodies in a neutral condition, or charged with the opposite electricity (negative or positive). But the transference is made much more readily to some substances than to others—so slowly, indeed, to some, that in ordinary experiments the transference may be regarded as not taking place at all. Substances of the former kind are called good conductors of electricity; those which receive the transfer of electricity less readily are said to be bad conductors; and those which scarcely receive it at all are called insulating substances. The reader must not confound the quality I am here speaking of with readiness to become charged with electricity. On the contrary, the bodies which most freely receive and transmit electricity are least readily charged with electricity, while insulating substances are readily electrified⁴³. Glass is an insulator⁴⁴, but if glass is briskly rubbed with silk it becomes charged (or rather, the part rubbed becomes charged) with positive electricity, formerly⁴⁵ called vitreous electricity for this reason; and again, if wax or resin⁴⁶, which are both good insulators⁴⁷, be rubbed with cloth or flannel⁴⁸, the part rubbed becomes charged with negative, formerly called resinous⁴⁹, electricity.

Electricity, then, positive or negative, however generated, passes freely along conducting substances, but is stopped by an insulating body, just as light passes through transparent⁵⁰ substances, but is stopped by an opaque⁵¹ body. Moreover, electricity may be made to pass to any distance along conducting bodies suitably insulated. Thus, it might seem that we have here the problem of distant communication solved. In fact, the first suggestion of the use of electricity in telegraphy was based on this property. When a charge of electricity has been obtained by the use of an ordinary electrical machine, this charge can be drawn⁵² off at a distant point, if a conducting channel properly insulated connects that point with the bodies (of whatever nature)239 which have been charged with electricity. In 1747, Dr. Watson exhibited electrical effects from the discharges of Leyden jars (vessels⁵³ suitably constructed to receive and retain electricity) at a distance of two miles from the electrical machine. In 1774, Le Sage¹⁰ proposed that by means of wires the electricity developed by an electrical machine should be transmitted by insulated wires to a point where an electroscope, or instrument for indicating the presence of electricity, should, by its movements, mark the letters of the alphabet, one wire being provided for each letter. In 1798 Béthencourt repeated Watson’s experiment, increasing the distance to twenty-seven miles, the extremities⁵⁵ of his line of communication being at Madrid and Aranjuez. (Guillemin, by the way, in his “Applications of the Physical Forces,” passes over Watson’s experiment; in fact, throughout his chapters on the electric telegraph, the steam-engine, and other subjects, he seems desirous of conveying as far as possible the impression that all the great advances of modern science had their origin in Paris and its neighbourhood.)

From Watson’s time until 1823 attempts were made in this country and on the Continent to make the electrical machine serve as the means of telegraphic communication. All the familiar phenomena of the lecture-room have been suggested as signals. The motion of pith balls, the electric spark, the perforation of paper by the spark, the discharge of sparks on a fulminating pane⁵⁶ (a glass sheet on which pieces of tinfoil⁵⁷ are suitably arranged, so that sparks passing from one to another form various figures or devices), and other phenomena, were proposed and employed experimentally. But practically these methods were not effectual. The familiar phenomenon of the electric spark explains the cause of failure. The spark indicates the passage of electricity across an insulating medium—dry air—when a good conductor approaches within a certain distance of the charged body. The greater the charge of electricity, the greater is the distance over which the electricity will thus make its escape. Insulation⁵⁸, then, for many miles of wire, and still240 more for a complete system of communication such as we now have, was hopeless, so long as frictional electricity was employed, or considerable electrical intensity⁶⁰ required.

We have now to consider how galvanic electricity, discovered in 1790, was rendered available for telegraphic communication. In the first place, let us consider what galvanic or voltaic electricity is.

I have said that electricity can be generated in many ways. It may be said, indeed, that every change in the condition of a substance, whether from mechanical causes, as, for instance, a blow, a series of small blows, friction⁵⁹, and so forth, or from change of temperature, moisture, and the like, or from the action of light, or from chemical processes, results in the development of more or less electricity.

When a plate of metal is placed in a vessel⁵⁴ containing some acid (diluted) which acts chemically on the metal, this action generates negative electricity, which passes away as it is generated. But if a plate of a different metal, either not chemically affected⁶² by the acid or less affected than the former, be placed in the dilute⁶¹ acid, the two plates being only partially⁶³ immersed and not in contact, then, when a wire is carried from one plate to the other, the excess of positive electricity in the plate least affected by the acid is conveyed to the other, or, in effect, discharged; the chemical action, however, continues, or rather is markedly increased, fresh electricity is generated, and the excess of positive electricity in the plate least affected is constantly discharged. Thus, along the wire connecting the two metals a current of electricity passes from the metal least affected to the metal most affected; a current of negative electricity passes in a contrary direction in the dilute acid.

I have spoken here of currents passing along the wire and in the acid, and shall have occasion hereafter to speak of the plate of metal least affected as the positive pole, this plate being regarded, in this case, as a source whence a current of positive electricity flows along the wire connection to the other plate, which is called the negative pole. But I241 must remind the reader that this is only a convenient way of expressing the fact that the wire assumes a certain condition when it connects two such plates, and is capable of producing certain effects. Whether in reality any process is taking place which can be justly compared to the flow of a current one way or the other, or whether a negative current flows along the circuit one way, while the positive current flows the other way, are questions still unanswered. We need not here enter into them, however. In fact, very little is known about these points. Nor need we consider here the various ways in which many pairs of plates such as I have described can be combined in many vessels of dilute acid to strengthen the current. Let it simply be noted⁶⁴ that such a combination is called a battery; that when the extreme plates of opposite kinds are connected by a wire, a current of electricity passes along the wire from the extreme plate of that metal which is least affected, forming the positive pole, to the other extreme plate of that metal which is most affected and forms the negative pole. The metals commonly employed are zinc⁶⁵ and copper⁶⁶, the former being the one most affected by the action of the dilute acid, usually sulphuric acid. But it must here be mentioned that the chemical process, affecting both metals, but one chiefly, would soon render a battery of the kind described useless; wherefore arrangements are made in various ways for maintaining the efficiency of the dilute acid and of the metallic⁶⁷ plates, especially the copper: for the action of the acid on the zinc tends, otherwise, to form on the copper a deposit of zinc. I need not describe the various arrangements for forming what are called constant batteries, as Daniell’s, Grove’s, Bunsen’s, and others. Let it be understood that, instead of a current which would rapidly grow weaker and weaker, these batteries give a steady current for a considerable time. Without this, as will presently be seen, telegraphic communication would be impossible.

We have, then, in a galvanic battery a steady source of electricity. This electricity is of low intensity, incompetent242 to produce the more striking phenomena of frictional electricity. Let us, however, consider how it would operate at a distance.

The current will pass along any length of conducting substance properly insulated. Suppose, then, an insulated wire passes from the positive pole of a battery at a station A to a station B, and thence back to the negative pole at the station A. Then the current passes along it, and this can be indicated at B by some action such as electricity of low intensity can produce. If now the continuity of the wire be interrupted close by the positive pole at A, the current ceases and the action is no longer produced. The observer at B knows then that the continuity of the wire has been interrupted; he has been, in fact, signalled to that effect.

But, as I have said, the electrical phenomena which can be produced by the current along a wire connecting the positive and negative poles of a galvanic battery are not striking. They do not afford effective signals when the distance traversed is very great and the battery not exceptionally strong. Thus, at first, galvanic electricity was not more successful in practice than frictional electricity.

It was not until the effect of the galvanic current on the magnetic needle had been discovered that electricity became practically available in telegraphy.

Oersted discovered in 1820 that a magnetic needle poised⁶⁸ horizontally is deflected⁶⁹ when the galvanic current passes above it (parallel to the needle’s length) or below it. If the current passes above it, the north end of the needle turns towards the east when the current travels from north to south, but towards the west when the current travels from south to north; on the other hand, if the current passes below the needle, the north end turns towards the west when the current travels from south to north, and towards the east when the current travels from north to south. The deflection will be greater or less according to the power of the current. It would be very slight indeed in the case of a needle, however243 delicately poised, above or below which passed a wire conveying a galvanic current from a distant station. But the effect can be intensified⁷¹, as follows:—
Fig³². 1.

Suppose a b c d e f to be a part of the wire from A to B, passing above a delicately poised magnetic needle N S, along a b and then below the needle along c d, and then above again along e f and so to the station B. Let a current traverse the wire in the direction shown by the arrows. Then N, the north end of the needle, is deflected towards the east by the current passing along a b. But it is also deflected to the east by the current passing along c d; for this produces a deflection the reverse of that which would be produced by a current in the same direction above the needle—that is, in direction b a, and therefore the same as that produced by the current along a b. The current along e f also, of course, produces a deflection of the end N towards the east. All three parts, then, a b, c d, e f, conspire⁷² to increase the deflection of the end N towards the east. If the wire were twisted once again round N S, the deflection would be further increased; and finally, if the wire be coiled in the way shown in Fig. 1, but with a great number of coils, the deflection of the north end towards the east, almost imperceptible without such coils, will become sufficiently⁷³ obvious. If the direction of the current be changed, the end N will be correspondingly deflected towards the west.

The needle need not be suspended horizontally. If it hang vertically⁷⁴, that is, turn freely on a horizontal axis⁷⁶, and the coil be carried round it as above described, the deflection of the upper end will be to the right or to the left, according to the direction of the current. The needle actually seen, moreover, is not the one acted upon by the244 current. This needle is inside the coil; the needle seen turns on the same axis, which projects through the coil.

If, then, the observer at the station B have a magnetic needle suitably suspended, round which the wire from the battery at A has been coiled, he can tell by the movement of the needle whether a current is passing along the wire in one direction or in the other; while if the needle is at rest he knows that no current is passing.
Fig. 2.
Fig. 3.

Now suppose that P and N, Fig. 2, are the positive and negative poles of a galvanic battery at A, and that a wire passes from P to the station B, where it is coiled round a needle suspended vertically at n, and thence passes to the negative pole N. Let the wire be interrupted at a b and also at c d. Then no current passes along the wire, and the needle n remains⁷⁷ at rest in a vertical⁷⁵ position. Now suppose the points a b connected by the wire a b, and at the same moment the points c d connected by the wire c d, then a current flows along P a b to B, as shown in Fig. 2, circuiting the coil round the needle n and returning by d c to N. The upper end of the needle is deflected to the right while this current continues to flow; returning to rest when the connection is broken at a b and c d. Next, let c b and a d be simultaneously245 connected as shown by the cross-lines in Fig. 3. (It will be understood that a d and b c do not touch each other where they cross.) The current will now flow from P along a d to B, circuiting round the needle n in a contrary direction to that in which it flowed in the former case, returning by b c to N. The upper end of the needle is deflected then to the left while the current continues to flow along this course.

I need not here describe the mechanical devices by which the connection at a b and c d can be instantly changed so that the current may flow either along a b and d c, as in Fig. 2, circuiting the needle in one direction, or along a d and b c, as in Fig. 3, circuiting the needle in the other direction. As I said at the outset, this paper is not intended to deal with details of construction, only to describe the general principles of telegraphic communication, and especially those points which have to be explained in order that recent inventions may be understood. The reader will see that nothing can be easier than so to arrange matters that, by turning a handle, either (1), a b and c d may be connected, or, (2), a d and c b, or, (3), both lines of communication interrupted. The mechanism⁷⁹ for effecting this is called a commutator.

Two points remain, however, to be explained: First, A must be a receiving station as well as a transmitting station; secondly⁸⁰, the wire connecting B with N, in Figs⁸¹. 2 and 3, can be dispensed⁸² with, for it is found that if at B the wire is carried down to a large metal plate placed some depth underground, while the wire at c is carried down to another plate similarly buried underground, the circuit is completed even better than along such a return wire as is shown in the figures. The earth either acts the part of a return wire, or else, by continually carrying off the electricity, allows the current to flow continuously along the single wire. We may compare the current carried along the complete wire circuit, to water circulating in a pipe extending continuously from a reservoir to a distance and back again to the reservoir. Water sucked up continuously at one end could be carried through the pipe so long as it was continuously246 returned to the reservoir at the other; but it could equally be carried through a pipe extending from that reservoir to some place where it could communicate with the open sea—the reservoir itself communicating with the open sea—an arrangement corresponding to that by which the return wire is dispensed with, and the current from the wire received into the earth.

The discovery that the return wire may be dispensed with was made by Steinheil in 1837.

The actual arrangement, then, is in essentials that represented in Fig. 4.
Fig. 4.

A and B are the two stations; P N is the battery at A, P′ N′ the battery at B; P′ P′ are the positive poles, N′ N′, the negative poles. At n is the needle of station A, at n′ the needle of station B. When the handle of the commutator is in its mean position—which is supposed to be the case at station B—the points b′ d′ are connected with each other, but neither with a′ nor c′; no current, then, passes from B to A, but station B is in a condition to receive messages. (If b′ and d′ were not connected, of course no messages could be received, since the current from A would be stopped at b′—which does not mean that it would pass round n′ to b′, but that, the passage being stopped at b′, the current would not flow at all.) When (the commutator at B being in its mean position, or d′ b′ connected, and communication with c′ and a′ interrupted) the handle of the commutator at A is turned247 from its mean position in one direction, a and b are connected, as are c and d—as shown in the figure—while the connection between b and d is broken. Thus the current passes from P by a and b, round the needle n; thence to station B, round needle n′, and by b′ and d′, to the earth plate G′; and so along the earth to G, and by d c, to the negative pole N. The upper end of the needle of both stations is deflected to the right by the passage of the current in this direction. When the handle of the commutator at A is turned in the other direction, b and c are connected, as also a and d; the current from P passes along a d to the ground plate G, thence to G′, along d′ b′, round the needle n′, back by the wire to the station A, where, after circuiting the needle n in the same direction as the needle n′, it travels by b and c to the negative pole N. The upper end of the needle, at both stations, is deflected to the left by the passage of the current in this direction.

It is easily seen that, with two wires and one battery, two needles can be worked at both stations, either one moving alone, or the other alone, or both together; but for the two to move differently, two batteries must be used. The systems by which either the movements of a single needle, or of a pair of needles, may be made to indicate the various letters of the alphabet, numerals, and so on, need not here be described. They are of course altogether arbitrary, except only that the more frequent occurrence of certain letters, as e, t, a, renders it desirable that these should be represented by the simplest symbols (as by a single deflection to right or left), while letters which occur seldom may require several deflections.

One of the inventions to which the title of this paper relates can now be understood.
 
Fig. 5.

In the arrangement described, when a message is transmitted, the needle of the sender vibrates synchronously⁸³ with the needle at the station to which the message is sent. Therefore, till that message is finished, none can be received at the transmitting station. In what is called duplex telegraphy,248 this state of things is altered, the needle at the sending station being left unaffected by the transmitted current, so as to be able to receive messages, and in self-recording⁸⁵ systems to record them. This is done by dividing the current from the battery into two parts of equal efficiency, acting⁸⁶ on the needle at the transmitting station in contrary directions, so that this needle remains unaffected, and ready to indicate signals from the distant station. The principle of this arrangement is indicated in Fig. 5. Here a b n represents the main wire of communication with the distant station, coiled round the needle of the transmitting station in one direction; the dotted lines indicate a finer short wire, coiled round the needle in a contrary direction. When a message is transmitted, the current along the main wire tends to deflect⁷⁰ the needle at n in one direction, while the current along the auxiliary⁸⁷ wire tends to deflect it in the other direction. If the thickness and length of the short wire are such as to make these two tendencies equal, the needle remains at rest, while a message is transmitted to the distant station along the main wire. In this state of things, if a current is sent from the distant station along the wire in the direction indicated by the dotted arrow, this current also circuits the auxiliary wire, but in the direction indicated by the arrows on the dotted curve, which is the same direction in which it circuits the main wire. Thus the needle is deflected, and a signal received. When the direction of the chief current at the transmitting station is reversed, so also is the direction of the artificial current, so that again the needle is balanced. Similarly, if the direction of the current from the distant station is reversed, so also is the direction in which this current traverses the auxiliary wire, so that again both effects conspire to deflect the needle.

249 There is, however, another way in which an auxiliary wire may be made to work. It may be so arranged that, when a message is transmitted, the divided current flowing equally in opposite directions, the instrument at the sending station is not affected; but that when the operator at the distant station sends a current along the main wire, this neutralizes⁸⁸ the current coming towards him, which current had before balanced the artificial current. The latter, being no longer counterbalanced, deflects⁸⁹ the needle; so that, in point of fact, by this arrangement, the signal received at a station is produced by the artificial current at that station, though of course the real cause of the signal is the transmission of the neutralizing⁹⁰ current from the distant station.

The great value of duplex telegraphy is manifest. Not only can messages be sent simultaneously⁷⁸ in both directions along the wire—a circumstance which of itself would double the work which the wire is capable of doing—but all loss of time in arranging about the order of outward and homeward messages is prevented. The saving of time is especially important on long lines, and in submarine telegraphy. It is also here that the chief difficulties of duplex telegraphy have been encountered. The chief current and the artificial current must exactly balance each other. For this purpose the flow along each must be equal. In passing through the long wire, the current has to encounter a greater resistance than in traversing the short wire; to compensate⁹¹ for this difference, the short wire must be much finer than the long one. The longer the main wire, the more delicate is the task of effecting an exact balance. But in the case of submarine wires, another and a much more serious difficulty has to be overcome. A land wire is well insulated. A submarine wire is separated by but a relatively⁹² moderate thickness of gutta-percha from water, an excellent conductor, communicating directly with the earth, and is, moreover, surrounded by a protecting sheathing⁹³ of iron wires, laid spirally round the core, within which lies the copper conductor. Such a cable, as Faraday long since showed,250 acts precisely as an enormous Leyden jar; or rather, Faraday showed that such a cable, without the wire sheathing, would act when submerged as a Leyden jar, the conducting wire acting as the interior metallic coating of such a jar, the gutta-percha as the glass of the jar (the insulating medium), and the water acting as the exterior⁹⁴ metallic coating. Wheatstone showed further that such a cable, with a wire sheathing, would act as a Leyden jar, even though not submerged, the metal sheathing taking the part of the exterior coating of the jar. Now, regarding the cable thus as a condenser⁹⁵, we see that the transmission of a current along it may in effect be compared with the passage of a fluid along a pipe of considerable capacity, into which and from which it is conveyed by pipes of small capacity. There will be a retardation⁹⁶ of the flow of water corresponding to the time necessary to fill up the large part of the pipe; the water may indeed begin to flow through as quickly as though there were no enlargement of the bore of the pipe, but the full flow from the further end will be delayed. Just so it is with a current transmitted through a submarine cable. The current travels instantly (or with the velocity⁹⁷ of freest electrical transmission) along the entire line; but it does not attain⁹⁸ a sufficient intensity to be recognized for some time, nor its full intensity till a still longer interval⁹⁹ has elapsed. The more delicate the means of recognizing its flow, the more quickly is the signal received. The time intervals¹⁰⁰ in question are not, indeed, very great. With Thomson’s mirror galvanometer, in which the slightest motion of the needle is indicated by a beam of light (reflected from a small mirror moving with the needle), the Atlantic cable conveys its signal from Valentia to Newfoundland in about one second, while with the less sensitive galvanometer before used the time would be rather more than two seconds.

Now, in duplex telegraphy the artificial current must be equal to the chief current in intensity all the time; so that, since in submarine telegraphy the current rises gradually to251 its full strength and as gradually subsides¹⁰¹, the artificial current must do the same. Reverting¹⁰² to the illustration derived¹⁰³ from the flow of water, if we had a small pipe the rapid flow through which was to carry as much water one way as the slow flow through a large pipe was to carry water the other way, then if the large pipe had a widening along one part of its long course the short pipe would require to have a similar widening along the corresponding part of its short course. And to make the illustration perfect, the widenings along the large pipe should be unequal in different parts of the pipe’s length; for the capacity of a submarine cable, regarded as a condenser, is different along different parts of its length. What is wanted, then, for a satisfactory system of duplex telegraphy in the case of submarine cables, is an artificial circuit which shall not only correspond as a whole to the long circuit, but shall reproduce at the corresponding parts of its own length all the varieties of capacity existing along various parts of the length of the submarine cable.

Several attempts have been made by electricians to accomplish this result. Let it be noticed that two points have to be considered: the intensity of the current’s action, which depends on the resistance it has to overcome in traversing the circuit; and the velocity of transmission, depending on the capacity of various parts of the circuit to condense or collect electricity. Varley, Stearn, and others have endeavoured by various combinations of condensers¹⁰⁴ with resistance coils to meet these two requisites¹⁰⁵. But the action of artificial circuits thus arranged was not sufficiently uniform. Recently Mr. J. Muirhead, jun., has met the difficulty in the following way (I follow partially the account given in the Times of February 3, 1877, which the reader will now have no difficulty in understanding):—He has formed his second circuit by sheets of paper prepared with paraffin, and having upon one side a strip of tinfoil, wound to and fro to represent resistance. Through this the artificial current is conducted. On the other side is a sheet of tinfoil252 to represent the sheathing,29 and to correspond to the capacity of the wire. Each sheet of paper thus prepared may be made to represent precisely a given length of cable, having enough tinfoil on one side to furnish the resistance, and on the other to furnish the capacity. A sufficient number of such sheets would exactly represent the cable, and thus the artificial or non-signalling part of the current would be precisely equivalent to the signalling part, so far as its action on the needle at the transmitting station was concerned. “The new plan was first tried on a working scale,” says the Times, “on the line between Marseilles and Bona; but it has since been brought into operation from Marseilles to Malta, from Suez to Aden, and lastly, from Aden to Bombay. On a recent occasion when there was a break-down upon the Indo-European line, the duplex system rendered essential service, and maintained telegraphic communication which would otherwise have been most seriously interfered¹⁰⁷ with.” The invention, we may well believe, “cannot fail to be highly profitable to the proprietors¹⁰⁸ of submarine cables,” or to bring about “before long a material reduction in the cost of messages from places beyond the seas.”
* * * * *

The next marvel of telegraphy to be described is the transmission of actual facsimiles of writings or drawings. So far as strict sequence of subject-matter is concerned, I ought, perhaps, at this point, to show how duplex telegraphy has been surpassed by a recent invention, enabling three or four or more messages to be simultaneously transmitted telegraphically. But it will be more convenient to consider this wonderful advance after I have described the methods by which facsimiles of handwriting, etc., are transmitted.

253 Hitherto we have considered the action of the electric current in deflecting¹⁰⁹ a magnetic needle to right or left, a method of communication leaving no trace of its transmission. We have now to consider a method at once simpler in principle and affording means whereby a permanent record can be left of each message transmitted.
 
Fig. 6.

If the insulated wire is twisted in the form of a helix or coil round a bar of soft iron, the bar becomes magnetized while the current is passing. If the bar be bent¹¹⁰ into the horse-shoe form, as in Fig. 6, where A C B represents the bar, a b c d e f the coil of insulated wire, the bar acts as a magnet while the current is passing along the coil, but ceases to do so as soon as the current is interrupted.30 If, then, we have a telegraphic wire from a distant station in electric connection with the wire a b c, the part e f descending¹¹¹ to an earth-plate, then, according as the operator at that distant station transmits or stops the current, the iron A C B is magnetized or demagnetized. The part C is commonly replaced by a flat piece of iron, as is supposed to be the case with the temporary magnets shown in Fig. 7, where this flat piece is below the coils.

So far back as 1838 this property was applied by Morse in America in the recording instrument which bears his name, and is now (with slight modifications¹¹²) in general use not only in America but on the Continent. The principle254 of this instrument is exceedingly simple. Its essential parts are shown in Fig. 7; H is the handle, H b the lever of the manipulator at the station A. The manipulator is shown in the position for receiving a message from the station B along the wire W. The handle H′ of the manipulator at the station B is shown depressed, making connection at a′ with the wire from the battery N′ P′. Thus a current passes through the handle to c′, along the wire to c and through b to the coil of the temporary magnet M, after circling which it passes to the earth at e and so by E′ to the negative pole N′. The passage of this current magnetizes M, which draws down the armature m. Thus the lever l, pulled down on this side, presses upwards the pointed¹¹³ style s against a strip of paper p which is steadily¹¹⁴ rolled off from the wheel W so long as a message is being received. (The mechanism for this purpose is not indicated in Fig. 7.) Thus, so long as the operator at B holds down the handle H′, the style s marks the moving strip of paper, the spring r, under the lever s l, drawing the style away so soon as the current ceases to flow and the magnet to act. If he simply depresses the handle for an instant, a dot is marked; if longer, a dash; and by various combinations of dots and dashes all the letters, numerals, etc., are indicated. When the operator at B has completed his message, the handle H′ being raised by the spring under it (to the position in which H is shown), a message can be received at B.
Fig. 7.

255 I have in the figure and description assumed that the current from either station acts directly on the magnet which works the recording style. Usually, in long-distance telegraphy, the current is too weak for this, and the magnet on which it acts is used only to complete the circuit of a local battery, the current from which does the real work of magnetizing M at A or M′ at B, as the case may be. A local battery thus employed is called a relay.

The Morse instrument will serve to illustrate the principle of the methods by which facsimiles are obtained. The details of construction are altogether different from those of the Morse instrument; they also vary greatly in different instruments, and are too complex to be conveniently described here. But the principle, which is the essential point, can be readily understood.

In working the Morse instrument, the operator at B depresses the handle H′. Suppose that this handle is kept depressed by a spring, and that a long strip of paper passing uniformly between the two points at a prevents contact. Then no current can pass. But if there is a hole in this paper, then when the hole reaches a the two metal points at a meet and the current passes. We have here the principle of the Bain telegraph. A long strip of paper is punched with round and long holes, corresponding to the dots and marks of a message by the Morse alphabet. As it passes between a metal wheel and a spring, both forming part of the circuit, it breaks the circuit until a hole allows the spring to touch the wheel, either for a short or longer time-interval, during which the current passes to the other station, where it sets a relay at work. In Bain’s system the message is received on a chemically prepared strip of paper, moving uniformly at the receiving station, and connected with the negative pole of the relay battery. When contact is made, the face of the paper is touched by a steel pointer connected with the positive pole, and the current which passes from the end of the pointer through256 the paper to the negative pole produces a blue mark on the chemically prepared paper.31

We see that by Bain’s arrangement a paper is marked with dots and lines, corresponding to round and elongated¹¹⁵ holes, in a ribbon of paper. It is only a step from this to the production of facsimiles of writings or drawings.

Suppose a sheet of paper so prepared as to be a conductor of electricity, and that a message is written on the paper with some non-conducting substance for ink. If that sheet were passed between the knobs at a (the handle H being pressed down by a spring), whilst simultaneously a sheet of Bain’s chemically prepared paper were passed athwart the steel pointer at the receiving station, there would be traced across the last-named paper a blue line, which would be broken at parts corresponding to those on the other paper where the non-conducting ink interrupted the current. Suppose the process repeated, each paper being slightly shifted so that the line traced across either would be parallel and very close to the former, but precisely corresponding as respects the position of its length. Then this line, also, on the recording paper will be broken at parts corresponding to those in which the line across the transmitting paper meets the writing. If line after line be drawn in this way till the entire breadth of the transmitting paper has been crossed by close parallel lines, the entire breadth of the receiving paper will be covered by closely marked blue lines except where the writing has broken the contact. Thus a negative facsimile of the writing will be found in the manner indicated in Figs. 8 and 9.32 In reality, in processes of this kind, the papers (unlike the ribbons on Bain’s telegraph) are not carried across in the way I have imagined, but are swept by257 successive strokes of a movable pointer, along which the current flows; but the principle is the same.
Fig. 8.
Fig. 9.

It is essential, in such a process as I have described, first, that the recording sheet should be carried athwart the pointer which conveys the marking current (or the pointer carried across the recording sheet) in precise accordance with the motion of the transmitting sheet athwart the wire or style which conveys the current to the long wire between the stations (or of this style across the transmitting sheet). The recording sheet and the transmitting sheet must also be shifted between each stroke by an equal amount. The latter point, is easily secured; the former is secured by causing the mechanism which gives the transmitting style its successive strokes to make and break circuit, by which a temporary magnet at the receiving station is magnetized and demagnetized; by the action of this magnet the recording pointer is caused to start on its motion athwart the receiving sheet, and moving uniformly it completes its thwart¹¹⁶ stroke at the same instant as the transmitting style.

Caselli’s pantelegraph admirably effects the transmission of facsimiles. The transmitting style is carried by the motion of a heavy pendulum¹¹⁷ in an arc of constant range over a cylindrical¹¹⁸ surface on which the paper containing the258 message, writing, or picture, is spread. As the swing of the pendulum begins, a similar pendulum at the receiving station begins its swing; the same break of circuit which (by demagnetizing a temporary magnet) releases one, releases the other also. The latter swings in an arc of precisely the same range, and carries a precisely similar style over a similar cylindrical surface on which is placed the prepared receiving paper. In fact, the same pendulum at either station is used for transmitting and for receiving facsimiles. Nay¹¹⁹, not only so, but each pendulum, as it swings, serves in the work both of transmitting and recording facsimiles. As it swings one way, it travels along a line over each of two messages or drawings, while the other pendulum in its synchronous⁸⁴ swing traces a corresponding line over each of two receiving sheets; and as it swings the other way, it traces a line on each of two receiving sheets, corresponding to the lines along which the transmitting style of the other is passing along two messages or drawings. Such, at least, is the way in which the instrument works in busy times. It can, of course, send a message, or two messages, without receiving any.33

In Caselli’s pantelegraph matters are so arranged that instead of a negative facsimile, like Fig. 9, a true facsimile is obtained in all respects except that the letters and figures are made by closely set dark lines instead of being dark throughout as in the message. The transmitting paper is conducting and the ink non-conducting, as in Bakewell’s original arrangement; but instead of the conducting paper completing the circuit for the distant station, it completes a short home circuit (so to speak) along which the current travels without entering on the distant circuit When the non-conducting ink breaks the short circuit, the current259 travels in the long circuit through the recording pointer at the receiving station; and a mark is thus made corresponding to the inked part of the transmitting sheet instead of the blank part, as in the older plan.

The following passage from Guillemin’s “Application of the Physical Forces” indicates the effectiveness of Caselli’s pantelegraph not only as respects the character of the message it conveys, but as to rapidity of transmission. (I alter the measures from the metric to our usual system of notation¹²⁰.34) “Nothing is simpler than the writing of the pantelegraph. The message when written is placed on the surface of the transmitting cylinder¹²¹. The clerk makes the warning signals, and then sets the pendulum going. The transmission of the message is accomplished¹²² automatically, without the clerk having any work to do, and consequently without [his] being obliged to acquire any special knowledge. Since two despatches may be sent at the same time—and since shorthand may be used—the rapidity of transmission may be considerable.” “The long pendulum of Caselli’s telegraph,” says M. Quet, “generally performs about forty oscillations a minute, and the styles trace forty broken lines, separated from each other by less than the hundredth part of an inch. In one minute the lines described by the style have ranged over a breadth of more than half an inch, and in twenty minutes of nearly 10? inches. As we can give the lines a length of 4? inches, it follows that in twenty minutes Caselli’s apparatus¹²⁴ furnishes the facsimile of the writing or drawing traced on a metallized plate 4? inches broad by 10? inches long. For clearness of reproduction, the original writing must be very legible and in large characters.” “Since 1865 the line from Paris to Lyons and Marseilles has been open to the public for the transmission of messages by this truly marvellous system.”

260 It will easily be seen that Caselli’s method is capable of many important uses besides the transmission of facsimiles of handwriting. For instance, by means of it a portrait of some person who is to be identified—whether fraudulent absconder¹²⁵, or escaped prisoner or lunatic, or wife who has eloped from her husband, or husband who has deserted¹²⁶ his wife, or missing child, and so on—can be sent in a few minutes to a distant city where the missing person is likely to be. All that is necessary is that from a photograph or other portrait an artist employed for the purpose at the transmitting station should, in bold and heavy lines, sketch the lineaments of the missing person on one of the prepared sheets, as in Fig. 10. The portrait at the receiving station will appear as in Fig. 11, and if necessary an artist at this station can darken the lines or in other ways improve the picture without altering the likeness¹²⁷.
Fig. 10.
Fig. 11.

261 But now we must turn to the greatest marvel of all—the transmission of tones, tunes¹²⁹, and words by the electric wire.

The transmission of the rhythm of an air is of course a very simple matter. I have seen the following passage from “Lardner’s Museum of Science and Art,” 1859, quoted as describing an anticipation¹³⁰ of the telephone, though in reality it only shows what every one who has heard a telegraphic indicator¹³¹ at work must have noticed, that the click of the instrument may be made to keep time with an air. “We were in the Hanover Street Office, when there was a pause in the business operations. Mr. M. Porter, of the office at Boston—the writer being at New York—asked what tune¹²⁸ we would have? We replied, ‘Yankee Doodle,’ and to our surprise he immediately complied with our request. The instrument, a Morse one, commenced drumming the notes of the tune as perfectly¹³² and distinctly as a skilful¹³³ drummer could have made them at the head of a regiment¹³⁴, and many will be astonished to hear that ‘Yankee Doodle’ can travel by lightning.... So perfectly and distinctly were the sounds of the tunes transmitted, that good instrumental performers could have no difficulty in keeping time with the instruments at this end of the wires.... That a pianist in London should execute a fantasia at Paris, Brussels, Berlin, and Vienna, at the same moment, and with the same spirit, expression, and precision as if the instruments at these distant places were under his fingers, is not only within the limits of practicability, but really presents no other difficulty than may arise from the expense of the performances. From what has just been stated, it is clear that the time of music has been already transmitted, and the production of the sounds does not offer any more difficulty than the printing of the letters of a despatch¹²³.” Unfortunately, Lardner omitted to describe how this easy task was to be achieved.

Reuss first in 1861 showed how a sound can be transmitted. At the sending station, according to his method, there is a box, into which, through a pipe in the side, the note to be transmitted is sounded. The box is open at the262 top, and across it, near the top, is stretched a membrane¹³⁵ which vibrates synchronously with the aerial vibrations¹³⁶ corresponding to the note. At the middle of the membrane, on its upper surface, is a small disc of metal, connected by a thin strip of copper with the positive pole of the battery at the transmitting station. The disc also, when the machine is about to be put in use, lightly touches a point on a metallic arm, along which (while this contact continues) the electric current passes to the wire communicating with the distant station. At that station the wire is carried in a coil round a straight rod of soft iron suspended horizontally in such a way as to be free to vibrate between two sounding-boards. After forming this coil, the wire which conveys the current passes to the earth-plate and so home. As already explained, while the current passes, the rod of iron is magnetized, but the rod loses its magnetization when the current ceases.

Now, when a note is sounded in the box at the transmitting station, the membrane vibrates, and at each vibration¹³⁷ the metal disc is separated from the point which it lightly touches when at rest. Thus contact is broken at regular intervals, corresponding to the rate of vibration due to the note. Suppose, for instance, the note C is sounded; then there are 256 complete vibrations in a second, the electric current is therefore interrupted and renewed, and the bar of soft iron magnetized and demagnetized, 256 times in a second. Now, it had been discovered by Page and Henry that when a bar of iron is rapidly magnetized and demagnetized, it is put into vibrations synchronizing¹³⁸ with the interruptions of the current, and therefore emits a note of the same tone as that which has been sounded into the transmitting box.

Professor Heisler, in his “Lehrbuch der technischen Physik,” 1866, wrote of Reuss’s telephone: “The instrument is still in its infancy¹³⁹; however, by the use of batteries of proper strength, it already transmits not only single musical tones, but even the most intricate melodies, sung at one end of the line, to the other, situated¹⁴⁰ at a great distance, and makes them perceptible there with all desirable distinctness.” Dr.263 Van der Weyde, of New York, states that, after reading an account of Reuss’s telephone, he had two such instruments constructed, and exhibited them at the meeting of the Polytechnic¹⁴¹ Club of the American Institute. “The original sounds were produced at the furthest extremity¹⁴² of the large building (the Cooper Institute), totally out of hearing of the Association; and the receiving instrument, standing¹⁰⁶ on the table in the lecture-room, produced, with a peculiar⁸ and rather nasal twang, the different tunes sung into the box at the other end of the line; not powerfully, it is true, but very distinctly and correctly. In the succeeding summer I improved the form of the box, so as to produce a more powerful vibration of the membrane. I also improved the receiving instrument by introducing several iron wires into the coil, so as to produce a stronger vibration. I submitted these, with some other improvements, to the meeting of the American Association for the Advancement¹⁴³ of Science, and on that occasion (now seven years ago) expressed the opinion that the instrument contained the germ of a new method of working the electric telegraph, and would undoubtedly¹⁴⁴ lead to further improvements in this branch of science.”

The telephonic successes recently achieved by Mr. Gray were in part anticipated by La Cour, of Copenhagen, whose method may be thus described: At the transmitting station a tuning-fork is set in vibration. At each vibration one of the prongs touches a fine strip of metal completing a circuit. At the receiving station the wire conveying the electric current is coiled round the prongs of another tuning-fork of the same tone, but without touching¹⁴⁵ them. The intermittent¹⁴⁶ current, corresponding as it does with the rate of vibration proper to the receiving fork, sets this fork in vibration; and in La Cour’s instrument the vibrations of the receiving fork were used to complete the circuit of a local battery. His object was not so much the production of tones as the use of the vibrations corresponding to different tones, to act on different receiving instruments. For only a fork corresponding to the sending fork could be set in vibration by the264 intermittent current resulting from the latter’s vibrations. So that, if there were several transmitting forks, each could send its own message at the same time, each receiving fork responding only to the vibrations of the corresponding transmitting fork. La Cour proposed, in fact, that his instrument should be used in combination with other methods of telegraphic communication. Thus, since the transmitting fork, whenever put in vibration, sets the local battery of the receiving station at work, it can be used to work a Morse instrument, or it could work an ordinary Wheatstone and Cook instrument, or it could be used for a pantelegraph. The same wire, when different forks are used, could work simultaneously several instruments at the receiving station. One special use indicated by La Cour was the adaptation of his system to the Caselli pantelegraph, whereby, instead of one style, a comb of styles might be carried over the transmitting and recording plates. It would be necessary, in all such applications of his method (though, strangely enough, La Cour’s description makes no mention of the point), that the vibrations of the transmitting fork should admit of being instantly stopped or “damped.”

Mr. Gray’s system is more directly telephonic, as aiming rather at the development of sound itself than at the transmission of messages by the vibrations corresponding to sound. A series of tuning-forks are used, which are set in separate vibration by fingering the notes of a key-board. The vibrations are transmitted to a receiving instrument consisting of a series of reeds, corresponding in note to the series of transmitting forks, each reed being enclosed in a sounding-box. These boxes vary in length from two feet to six inches, and are connected by two wooden bars, one of which carries an electro-magnet, round the coils of which pass the currents from the transmitting instrument. When a tuning-fork is set in vibration by the performer at the transmitting key-board, the electro-magnet is magnetized and demagnetized synchronously with the vibrations of the fork. Not only are vibrations thus imparted to the reed of265 corresponding note, but these are synchronously strengthened by thuds resulting from the lengthening¹⁴⁷ of the iron when magnetized.

So far as its musical capabilities¹⁴⁸ are concerned, Gray’s telephone can hardly be regarded as fulfilling all the hopes that have been expressed concerning telephonic music. “Dreaming enthusiasts¹⁴⁹ of a prophetic turn of mind foretold,” we learn, “that a time would come when future Pattis would sing on a London stage to audiences in New York, Berlin, St. Petersburg, Shanghai, San Francisco, and Constantinople all at once.” But the account of the first concert given at a distance scarcely realizes these fond expectations. When “Home, Sweet Home,” played at Philadelphia, came floating through the air at the Steinway Hall, New York, “the sound was like that of a distant organ, rather faint, for a hard storm was in progress, and there was consequently a great leakage¹⁵⁰ of the electric current, but quite clear and musical. The lower notes were the best, the higher being sometimes almost inaudible. ‘The Last Rose of Summer,’ ‘Com’ è gentil,’ and other melodies, followed, with more or less success. There was no attempt to play chords,” though three or four notes can be sounded together. It must be confessed that the rosy¹⁵¹ predictions of M. Strakosch (the impresario) “as to the future of this instrument seem rather exalted¹⁵², and we are not likely as yet to lay on our music from a central reservoir as we lay on gas and water, though the experiment was certainly a very curious one.”

The importance of Mr. Gray’s, as of La Cour’s inventions, depends, however, far more on the way in which they increase the message-bearing capacity of telegraphy than on their power of conveying airs to a distance. At the Philadelphia Exhibition, Sir W. Thomson heard four messages sounded simultaneously by the Gray telephone. The Morse alphabet was used. I have mentioned that in that alphabet various combinations of dots and dashes are used to represent different letters; it is only necessary to substitute the short and long duration of a note for dots and dashes to have a266 similar sound alphabet. Suppose, now, four tuning-forks at the transmitting station, whose notes are Do Do, Mi, Sol, and Do Do, or say C, E, G, and C′, then by each of these forks a separate message may be transmitted, all the messages being carried simultaneously by the same line to separate sounding reeds (or forks, if preferred), and received by different clerks. With a suitable key-board, a single clerk could send the four messages simultaneously, striking chords instead of single notes, though considerable practice would be necessary to transform four verbal messages at once into the proper telephonic music, and some skill in fingering to give the proper duration to each note.

Lastly, we come to the greatest achievement of all, Professor Graham Bell’s vocal¹⁵³ telephone. In the autumn of 1875 I had the pleasure of hearing from Professor Bell in the course of a ride—all too short—from Boston to Salem, Mass., an account of his instrument as then devised, and of his hopes as to future developments. These hopes have since been in great part fulfilled, but I venture to predict that we do not yet know all, or nearly all, that the vocal telephone, in Bell’s hands, is to achieve.

It ought to be mentioned at the outset that Bell claims to have demonstrated in 1873 (a year before La Cour) the possibility of transmitting several messages simultaneously by means of the Morse alphabet.

Bell’s original arrangement for vocal telephony was as follows:—At one station a drumhead of goldbeaters’ skin, about 2? inches in diameter, was placed in front of an electro-magnet. To the middle of the drumhead, on the side towards the magnet, was glued a circular piece of clockspring. A similar electro-magnet, drumhead, etc., were placed at the other station. When notes were sung or words spoken before one drumhead, the vibrations of the goldbeaters’ skin carried the small piece of clockspring267 vibratingly towards and from the electro-magnet, without producing actual contact. Now, the current which was passing along the coil round the electro-magnet changed in strength with each change of position of this small piece of metal. The more rapid the vibrations, and the greater their amplitude¹⁵⁴, the more rapid and the more intense were the changes in the power of the electric current. Thus, the electro-magnet at the other station underwent changes of power which were synchronous with, and proportionate to, those changes of power in the current which were produced by the changes of position of the vibrating piece of clockspring. Accordingly, the piece of clockspring at the receiving station, and with it the drumhead there, was caused by the electro-magnet to vibrate with the same rapidity and energy as the piece at the transmitting station. Therefore, as the drumhead at one station varied¹⁵⁵ its vibrations in response to the sounds uttered in its neighbourhood, so the drumhead at the other station, varying its vibrations, emitted similar sounds. Later, the receiving drumhead was made unlike the transmitting one. Instead of a membrane carrying a small piece of metal, a thin and very flexible disc of sheet-iron, held in position by a screw, was used. This disc, set in vibration by the varying action of an electro-magnet, as in the older arrangement, uttered articulate sounds corresponding to those which, setting in motion the membrane at the transmitting station, caused the changes in the power of the electric current and in the action of the electro-magnet.

At the meeting of the British Association in 1876 Sir W. Thomson gave the following account of the performance of this instrument at the Philadelphia Exhibition:—“In the Canadian department” (for Professor Bell was not at the time an American citizen) “I heard ‘To be or not to be—there’s the rub,’ through the electric wire; but, scorning monosyllables, the electric articulation¹⁵⁶ rose to higher flights, and gave me passages taken at random¹⁵⁷ from the New York newspapers:—‘S. S. Cox has arrived’ (I failed to make out268 the ‘S. S. Cox’), ‘the City of New York,’ ‘Senator Morton,’ ‘the Senate has resolved to print a thousand extra copies,’ ‘the Americans in London have resolved to celebrate the coming Fourth of July.’ All this my own ears heard spoken to me with unmistakable distinctness by the thin circular disc armature of just such another little electro-magnet as this which I hold in my hand. The words were shouted with a clear and loud voice by my colleague judge, Professor Watson, at the far end of the line, holding his mouth close to a stretched membrane, carrying a piece of soft iron, which was thus made to perform in the neighbourhood of an electro-magnet, in circuit with the line, motions proportional to the sonorific motions of the air. This, the greatest by far of all the marvels of the electric telegraph, is due to a young countryman of our own, Mr. Graham Bell, of Edinburgh, and Montreal, and Boston, now about to become a naturalized citizen of the United States. Who can but admire the hardihood of invention which devised such very slight means to realize the mathematical conception that, if electricity is to convey all the delicacies¹⁵⁸ of quality which distinguish articulate speech, the strength of its current must vary continuously, and as nearly as may be in simple proportion to the velocity of a particle of air engaged in constituting the sound?”

Since these words were spoken by one of the highest authorities in matters telegraphic, Professor Bell has introduced some important modifications in his apparatus. He now employs, not an electro-magnet, but a permanent magnet. That is to say, instead of using at each station such a bar of soft iron as is shown in Fig. 6, which becomes a magnet while the electric current is passing through the coil surrounding it, he uses at each station a bar of iron permanently¹⁵⁹ magnetized (or preferably a powerful magnet made of several horse-shoe bars—that is, a compound magnet), surrounded similarly by coils of wire. No battery is needed. Instead of a current through the coils magnetizing the iron, the iron already magnetized causes a current269 to traverse the coils whenever it acts, or rather whenever its action changes. If an armature were placed across its ends or poles, at the moment when it drew that armature to the poles by virtue¹⁶⁰ of its magnetic power, a current would traverse the coils; but afterwards, so long as the armature remained there, there would be no current. If an armature placed near the poles were shifted rapidly in front of the poles, currents would traverse the coils, or be induced, their intensity depending on the strength of the magnet, the length of the coil, and the rapidity and range of the motions. In front of the poles of the magnet is a diaphragm of very flexible iron (or else some other flexible material bearing a small piece of iron on the surface nearest the poles). A mouthpiece to converge¹⁶¹ the sound upon this diaphragm substantially completes the apparatus at each station. Professor Bell thus describes the operation of the instrument:—“The motion of steel or iron in front of the poles of a magnet creates a current of electricity in coils surrounding the poles of the magnet, and the duration of this current of electricity coincides with the duration of the motion of the steel or iron moved or vibrated in the proximity¹⁶² of the magnet. When the human voice causes the diaphragm to vibrate, electrical undulations are induced in the coils around the magnets precisely similar to the undulations of the air produced by the voice. The coils are connected with the line wire, and the undulations induced in them travel through the wire, and, passing through the coils of another instrument of similar construction at the other end of the line, are again resolved into air undulations by the diaphragm of this (other) instrument.”

So perfectly are the sound undulations repeated—though the instrument has not yet assumed its final form—that not only has the lightest whisper uttered at one end of a line of 140 miles been distinctly heard at the other, but the speaker can be distinguished¹⁶³ by his voice when he is known to the listener. So far as can be seen, there is every room to believe that before long Professor Bell’s grand invention will270 be perfected to such a degree that words uttered on the American side of the Atlantic will be heard distinctly after traversing 2000 miles under the Atlantic, at the European end of the submarine cable—so that Sir W. Thomson at Valentia could tell by the voice whether Graham Bell, or Cyrus Field, or his late colleague Professor Watson, were speaking to him from Newfoundland. Yet a single wave of those which toss in millions on the Atlantic, rolling in on the Irish strand¹⁶⁴, would utterly drown the voices thus made audible after passing beneath two thousand miles of ocean.

Here surely is the greatest of telegraphic achievements. Of all the marvels of telegraphy—and they are many—none are equal to, none seem even comparable with, this one. Strange truly is the history of the progress of research which has culminated¹⁶⁵ in this noble triumph, wonderful the thought that from the study of the convulsive twitchings of a dead frog by Galvani, and of the quivering of delicately poised magnetic needles by Ampère, should gradually have arisen through successive developments a system of communication so perfect and so wonderful as telegraphy has already become, and promising¹⁶⁶ yet greater marvels in the future.

The last paragraph had barely been written when news arrived of another form of telephone, surpassing Gray’s and La Cour’s in some respects as a conveyor of musical tones, but as yet unable to speak like Bell’s. It is the invention of Mr. Edison, an American electrician. He calls it the motograph. He discovered about six years ago the curious property on which the construction of the instrument depends. If a piece of paper moistened with certain chemical solutions is laid upon a metallic plate connected with the positive pole of a galvanic battery, and a platinum¹⁶⁷ wire connected with the negative pole is dragged over the moistened paper, the wire slides over the paper like smooth iron over ice—the usual friction disappearing so long as the current is passing from the wire to the plate through271 the paper. At the receiving station of Mr. Edison’s motograph there is a resonating box, from one face of which extends a spring bearing a platinum point, which is pressed by the spring upon a tape of chemically prepared paper. This tape is steadily unwound, drawing by its friction the platinum point, and with it the face of the resonator, outwards¹⁶⁸. This slight strain on the face of the resonator continues so long as no current passes from the platinum point to the metallic drum over which the moistened tape is rolling. But so soon as a current passes, the friction immediately ceases, and the face of the resonator resumes its normal position. If then at the transmitting station there is a membrane or a very fine diaphragm (as in Reuss’s or Bell’s arrangement) which is set vibrating by a note of any given tone, the current, as in those arrangements, is transmitted and stopped at intervals corresponding to the tone, and the face of the resonating box is freed and pulled at the same intervals. Hence, it speaks the corresponding tone. The instrument appears to have the advantage over Gray’s in range. In telegraphic communication Gray’s telephone is limited to about one octave. Edison’s extends from the deepest bass¹⁶⁹ notes to the highest notes of the human voice, which, when magnets are employed, are almost inaudible. But Edison’s motograph has yet to learn to speak.

Other telegraphic marvels might well find a place here. I might speak of the wonders of submarine telegraphy, and of the marvellous delicacy¹⁷⁰ of the arrangements by which messages by the Atlantic Cable are read, and not only read, but made to record themselves. I might dwell, again, on the ingenious printing telegraph of Mr. Hughes, which sets up its own types, inks them, and prints them, or on the still more elaborate plan of the Chevalier Bonelli “for converting the telegraph stations into so many type-setting workshops.” But space would altogether fail me to deal properly with these and kindred marvels. There is, however, one application of telegraphy, especially interesting272 to the astronomer, about which I must say a few words: I mean, the employment of electricity as a regulator of time. Here again it is the principle of the system, rather than details of construction, which I propose to describe. Suppose we have a clock not only of excellent construction, but under astronomical¹⁷¹ surveillance, so that when it is a second or so in error it is set right again by the stars. Let the pendulum of this clock beat seconds; and at each beat let a galvanic current be made and broken. This may be done in many ways—thus the pendulum may at each swing tilt¹⁷² up a very light metallic hammer, which forms part of the circuit when down; or the end of the pendulum may be covered with some non-conducting substance which comes at each swing between two metallic springs in very light contact, separating them and so breaking circuit; or in many other ways the circuit may be broken. When the circuit is made, let the current travel along a wire which passes through a number of stations near or remote, traversing at each the coils of a temporary magnet. Then, at each swing of the pendulum of the regulating clock, each magnet is magnetized and demagnetized. Thus each, once in a second, draws to itself, and then releases its armature, which is thereupon pulled back by a spring. Let the armature, when drawn to the magnet, move a lever by which one tooth of a wheel is carried forward. Then the wheel is turned at the rate of one tooth per second. This wheel communicates motion to others in the usual way. In fact, we have at each station a clock driven, not by a weight or spring and with a pendulum which allows one tooth of an escapement wheel to pass at each swing, but by the distant regulating clock which turns a driving wheel at the rate of one tooth per second, that is, one tooth for each swing of the regulating clock’s pendulum. Each clock, then, keeps perfect time with the regulating clock. In astronomy, where it is often of the utmost importance to secure perfect synchronism of observation, or the power of noting the exact difference of time between observations273 made at distant stations, not only can the same clock thus keep time for two observers hundreds of miles apart, but each observer can record by the same arrangement the moment of the occurrence of some phenomenon. For if a tape be unwound automatically, as in the Morse instrument, it is easy so to arrange matters that every second’s beat of the pendulum records itself by a dot or short line on the tape, and that the observer can with a touch make (or break) contact at the instant of observation, and so a mark be made properly placed between two seconds’ marks—thus giving the precise time when the observation was made. Such applications, however, though exceedingly interesting to astronomers¹⁷³, are not among those in which the general public take chief interest. There was one occasion, however, when astronomical time-relations were connected in the most interesting manner with one of the greatest of all the marvels of telegraphy: I mean, when the Great Eastern in mid-ocean was supplied regularly with Greenwich time, and this so perfectly (and therefore with such perfect indication of her place in the Atlantic), that when it was calculated from the time-signals that the buoy¹⁷⁴ left in open ocean to mark the place of the cut cable had been reached, and the captain was coming on deck with several officers to look for it, the buoy announced its presence by thumping¹⁷⁵ the side of the great ship.

1 marvels   

n.奇迹( marvel的名词复数 )；令人惊奇的事物（或事例）；不平凡的成果；成就v.惊奇，对…感到惊奇( marvel的第三人称单数 )

参考例句：

• The doctor's treatment has worked marvels : the patient has recovered completely. 该医生妙手回春，病人已完全康复。 来自辞典例句
• Nevertheless he revels in a catalogue of marvels. 可他还是兴致勃勃地罗列了一堆怪诞不经的事物。 来自辞典例句

2 marvel   

vi.(at)惊叹vt.感到惊异；n.令人惊异的事

参考例句：

• The robot is a marvel of modern engineering.机器人是现代工程技术的奇迹。
• The operation was a marvel of medical skill.这次手术是医术上的一个奇迹。

3 utterly   

adv.完全地，绝对地

参考例句：

• Utterly devoted to the people,he gave his life in saving his patients.他忠于人民，把毕生精力用于挽救患者的生命。
• I was utterly ravished by the way she smiled.她的微笑使我完全陶醉了。

4 interpretation   

n.解释，说明，描述；艺术处理

参考例句：

• His statement admits of one interpretation only.他的话只有一种解释。
• Analysis and interpretation is a very personal thing.分析与说明是个很主观的事情。

5 physicists   

物理学家( physicist的名词复数 )

参考例句：

• For many particle physicists, however, it was a year of frustration. 对于许多粒子物理学家来说，这是受挫折的一年。 来自英汉非文学 - 科技
• Physicists seek rules or patterns to provide a framework. 物理学家寻求用法则或图式来构成一个框架。

6 unfamiliar   

adj.陌生的，不熟悉的

参考例句：

• I am unfamiliar with the place and the people here.我在这儿人地生疏。
• The man seemed unfamiliar to me.这人很面生。

7 peculiarities   

n. 特质, 特性, 怪癖, 古怪

参考例句：

• the cultural peculiarities of the English 英国人的文化特点
• He used to mimic speech peculiarities of another. 他过去总是模仿别人讲话的特点。

8 peculiar   

adj.古怪的，异常的；特殊的，特有的

参考例句：

• He walks in a peculiar fashion.他走路的样子很奇特。
• He looked at me with a very peculiar expression.他用一种很奇怪的表情看着我。

9 astronomer   

n.天文学家

参考例句：

• A new star attracted the notice of the astronomer.新发现的一颗星引起了那位天文学家的注意。
• He is reputed to have been a good astronomer.他以一个优秀的天文学者闻名于世。

10 sage   

n.圣人，哲人；adj.贤明的，明智的

参考例句：

• I was grateful for the old man's sage advice.我很感激那位老人贤明的忠告。
• The sage is the instructor of a hundred ages.这位哲人是百代之师。

11 mere   

adj.纯粹的；仅仅，只不过

参考例句：

• That is a mere repetition of what you said before.那不过是重复了你以前讲的话。
• It's a mere waste of time waiting any longer.再等下去纯粹是浪费时间。

12 applied   

adj.应用的；v.应用，适用

参考例句：

• She plans to take a course in applied linguistics.她打算学习应用语言学课程。
• This cream is best applied to the face at night.这种乳霜最好晚上擦脸用。

13 celestial   

adj.天体的；天上的

参考例句：

• The rosy light yet beamed like a celestial dawn.玫瑰色的红光依然象天上的朝霞一样绚丽。
• Gravity governs the motions of celestial bodies.万有引力控制着天体的运动。

14 orbs   

abbr.off-reservation boarding school 在校寄宿学校n.球，天体，圆形物( orb的名词复数 )

参考例句：

• So strange did It'seem that those dark wild orbs were ignorant of the day. 那双狂热的深色眼珠竟然没有见过天日，这似乎太奇怪了。 来自辞典例句
• HELPERKALECGOSORB01.wav-> I will channel my power into the orbs! Be ready! 我会把我的力量引导进宝珠里！准备！ 来自互联网

15 scrutiny   

n.详细检查，仔细观察

参考例句：

• His work looks all right,but it will not bear scrutiny.他的工作似乎很好，但是经不起仔细检查。
• Few wives in their forties can weather such a scrutiny.很少年过四十的妻子经得起这么仔细的观察。

16 sketch   

n.草图；梗概；素描；v.素描；概述

参考例句：

• My sister often goes into the country to sketch. 我姐姐常到乡间去写生。
• I will send you a slight sketch of the house.我将给你寄去房屋的草图。

17 precisely   

adv.恰好，正好，精确地，细致地

参考例句：

• It's precisely that sort of slick sales-talk that I mistrust.我不相信的正是那种油腔滑调的推销宣传。
• The man adjusted very precisely.那个人调得很准。

18 detailed   

adj.详细的，详尽的，极注意细节的，完全的

参考例句：

• He had made a detailed study of the terrain.他对地形作了缜密的研究。
• A detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。

19 insufficient   

adj.(for，of)不足的，不够的

参考例句：

• There was insufficient evidence to convict him.没有足够证据给他定罪。
• In their day scientific knowledge was insufficient to settle the matter.在他们的时代，科学知识还不能足以解决这些问题。

20 deter   

vt.阻止，使不敢，吓住

参考例句：

• Failure did not deter us from trying it again.失败并没有能阻挡我们再次进行试验。
• Dogs can deter unwelcome intruders.狗能够阻拦不受欢迎的闯入者。

21 frankly   

adv.坦白地，直率地；坦率地说

参考例句：

• To speak frankly, I don't like the idea at all.老实说，我一点也不赞成这个主意。
• Frankly speaking, I'm not opposed to reform.坦率地说，我不反对改革。

22 thoroughly   

adv.完全地，彻底地，十足地

参考例句：

• The soil must be thoroughly turned over before planting.一定要先把土地深翻一遍再下种。
• The soldiers have been thoroughly instructed in the care of their weapons.士兵们都系统地接受过保护武器的训练。

23 Dispersive   

adj. 分散的

参考例句：

• In many atomic fluorescence applications a non-dispersive optical system may be used. 在许多原子荧光法的应用中，可以采用非分散的光学系统。
• The wave are of course dispersive. 当然这种波是弥散的。

24 observatory   

n.天文台，气象台，瞭望台，观测台

参考例句：

• Guy's house was close to the observatory.盖伊的房子离天文台很近。
• Officials from Greenwich Observatory have the clock checked twice a day.格林威治天文台的职员们每天对大钟检查两次。

25 spectrum   

n.谱，光谱，频谱；范围，幅度，系列

参考例句：

• This is a kind of atomic spectrum.这是一种原子光谱。
• We have known much of the constitution of the solar spectrum.关于太阳光谱的构成，我们已了解不少。

26 briefly   

adv.简单地，简短地

参考例句：

• I want to touch briefly on another aspect of the problem.我想简单地谈一下这个问题的另一方面。
• He was kidnapped and briefly detained by a terrorist group.他被一个恐怖组织绑架并短暂拘禁。

27 beacon   

n.烽火，（警告用的）闪火灯，灯塔

参考例句：

• The blink of beacon could be seen for miles.灯塔的光亮在数英里之外都能看见。
• The only light over the deep black sea was the blink shone from the beacon.黑黢黢的海面上唯一的光明就只有灯塔上闪现的亮光了。

28 favourable   

adj.赞成的，称赞的，有利的，良好的，顺利的

参考例句：

• The company will lend you money on very favourable terms.这家公司将以非常优惠的条件借钱给你。
• We found that most people are favourable to the idea.我们发现大多数人同意这个意见。

29 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

30 depressed   

adj.沮丧的，抑郁的，不景气的，萧条的

参考例句：

• When he was depressed,he felt utterly divorced from reality.他心情沮丧时就感到完全脱离了现实。
• His mother was depressed by the sad news.这个坏消息使他的母亲意志消沉。

31 forth   

adv.向前；向外，往外

参考例句：

• The wind moved the trees gently back and forth.风吹得树轻轻地来回摇晃。
• He gave forth a series of works in rapid succession.他很快连续发表了一系列的作品。

32 fig   

n.无花果(树)

参考例句：

• The doctor finished the fig he had been eating and selected another.这位医生吃完了嘴里的无花果，又挑了一个。
• You can't find a person who doesn't know fig in the United States.你找不到任何一个在美国的人不知道无花果的。

33 previously   

adv.以前，先前（地）

参考例句：

• The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
• Let me digress for a moment and explain what had happened previously.让我岔开一会儿，解释原先发生了什么。

34 secrecy   

n.秘密，保密，隐蔽

参考例句：

• All the researchers on the project are sworn to secrecy.该项目的所有研究人员都按要求起誓保守秘密。
• Complete secrecy surrounded the meeting.会议在绝对机密的环境中进行。

35 planks   

（厚）木板( plank的名词复数 )； 政纲条目，政策要点

参考例句：

• The house was built solidly of rough wooden planks. 这房子是用粗木板牢固地建造的。
• We sawed the log into planks. 我们把木头锯成了木板。

36 gallows   

n.绞刑架，绞台

参考例句：

• The murderer was sent to the gallows for his crimes.谋杀犯由于罪大恶极被处以绞刑。
• Now I was to expiate all my offences at the gallows.现在我将在绞刑架上赎我一切的罪过。

37 upwards   

adv.向上，在更高处...以上

参考例句：

• The trend of prices is still upwards.物价的趋向是仍在上涨。
• The smoke rose straight upwards.烟一直向上升。

38 downwards   

adj./adv.向下的（地），下行的（地）

参考例句：

• He lay face downwards on his bed.他脸向下伏在床上。
• As the river flows downwards,it widens.这条河愈到下游愈宽。

39 proceeding   

n.行动，进行，(pl.)会议录，学报

参考例句：

• This train is now proceeding from Paris to London.这次列车从巴黎开往伦敦。
• The work is proceeding briskly.工作很有生气地进展着。

40 illustrate   

v.举例说明，阐明；图解，加插图

参考例句：

• The company's bank statements illustrate its success.这家公司的银行报表说明了它的成功。
• This diagram will illustrate what I mean.这个图表可说明我的意思。

41 underlying   

adj.在下面的，含蓄的，潜在的

参考例句：

• The underlying theme of the novel is very serious.小说隐含的主题是十分严肃的。
• This word has its underlying meaning.这个单词有它潜在的含义。

42 phenomena   

n.现象

参考例句：

• Ade couldn't relate the phenomena with any theory he knew.艾德无法用他所知道的任何理论来解释这种现象。
• The object of these experiments was to find the connection,if any,between the two phenomena.这些实验的目的就是探索这两种现象之间的联系，如果存在着任何联系的话。

43 electrified   

v.使电气化( electrify的过去式和过去分词 )；使兴奋

参考例句：

• The railway line was electrified in the 1950s. 这条铁路线在20世纪50年代就实现了电气化。
• The national railway system has nearly all been electrified. 全国的铁路系统几乎全部实现了电气化。 来自《简明英汉词典》

44 insulator   

n.隔离者；绝缘体

参考例句：

• Few substances can equal fur as an insulator.作为绝缘体很少有其他材料能与动物皮毛相媲美。
• A loose mulch acts on the surface as an insulator.疏松的覆盖物在土壤表面起了隔热的作用。

45 formerly   

adv.从前，以前

参考例句：

• We now enjoy these comforts of which formerly we had only heard.我们现在享受到了过去只是听说过的那些舒适条件。
• This boat was formerly used on the rivers of China.这船从前航行在中国内河里。

46 resin   

n.树脂，松香，树脂制品；vt.涂树脂

参考例句：

• This allyl type resin is a highly transparent, colourless material.这种烯丙基型的树脂是一种高度透明的、无色材料。
• This is referred to as a thixotropic property of the resin.这种特性叫做树脂的触变性。

47 insulators   

绝缘、隔热或隔音等的物质或装置( insulator的名词复数 )

参考例句：

• There is no sharp line separating conductors from insulators. 实际上并没有一个明显的界限将半导体和绝缘体分开。
• To reduce heat losses the pipes are covered by thermal insulators. 为了减少热散失，管子外包保温层。

48 flannel   

n.法兰绒；法兰绒衣服

参考例句：

• She always wears a grey flannel trousers.她总是穿一条灰色法兰绒长裤。
• She was looking luscious in a flannel shirt.她穿着法兰绒裙子，看上去楚楚动人。

49 resinous   

adj.树脂的，树脂质的，树脂制的

参考例句：

• Alcohol is a solvent of resinous substances.酒精是树脂性物质的溶媒。
• He observed that the more resinous the wood, the more resistant it was to decay.他观察到木材含树脂越多，其抗腐力越强。

50 transparent   

adj.明显的，无疑的；透明的

参考例句：

• The water is so transparent that we can see the fishes swimming.水清澈透明，可以看到鱼儿游来游去。
• The window glass is transparent.窗玻璃是透明的。

51 opaque   

adj.不透光的；不反光的，不传导的；晦涩的

参考例句：

• The windows are of opaque glass.这些窗户装着不透明玻璃。
• Their intentions remained opaque.他们的意图仍然令人费解。

52 drawn   

v.拖，拉，拔出；adj.憔悴的，紧张的

参考例句：

• All the characters in the story are drawn from life.故事中的所有人物都取材于生活。
• Her gaze was drawn irresistibly to the scene outside.她的目光禁不住被外面的风景所吸引。

53 vessels   

n.血管( vessel的名词复数 )；船；容器；（具有特殊品质或接受特殊品质的）人

参考例句：

• The river is navigable by vessels of up to 90 tons. 90 吨以下的船只可以从这条河通过。 来自《简明英汉词典》
• All modern vessels of any size are fitted with radar installations. 所有现代化船只都有雷达装置。 来自《现代汉英综合大词典》

54 vessel   

n.船舶；容器，器皿；管，导管，血管

参考例句：

• The vessel is fully loaded with cargo for Shanghai.这艘船满载货物驶往上海。
• You should put the water into a vessel.你应该把水装入容器中。

55 extremities   

n.端点( extremity的名词复数 )；尽头；手和足；极窘迫的境地

参考例句：

• She was most noticeable, I thought, in respect of her extremities. 我觉得她那副穷极可怜的样子实在太惹人注目。 来自辞典例句
• Winters may be quite cool at the northwestern extremities. 西北边区的冬天也可能会相当凉。 来自辞典例句

56 pane   

n.窗格玻璃，长方块

参考例句：

• He broke this pane of glass.他打破了这块窗玻璃。
• Their breath bloomed the frosty pane.他们呼出的水气，在冰冷的窗玻璃上形成一层雾。

57 tinfoil   

n.锡纸，锡箔

参考例句：

• You can wrap it up in tinfoil.你可以用锡箔纸裹住它。
• Drop by rounded tablespoon onto tinfoil.Bake for 9 to 11 minutes or until golden brown.用大餐勺把刚刚搅拌好的糊糊盛到锡纸上，烘烤9至11分钟，直到变成金黄色。

58 insulation   

n.隔离；绝缘；隔热

参考例句：

• Please examine the insulation of the electric wires in my house.请检查一下我屋子里电线的绝缘情况。
• It is always difficult to assure good insulation between the electric leads.要保证两个电触头之间有良好的绝缘总是很困难的。

59 friction   

n.摩擦，摩擦力

参考例句：

• When Joan returned to work,the friction between them increased.琼回来工作后，他们之间的摩擦加剧了。
• Friction acts on moving bodies and brings them to a stop.摩擦力作用于运动着的物体，并使其停止。

60 intensity   

n.强烈，剧烈；强度；烈度

参考例句：

• I didn't realize the intensity of people's feelings on this issue.我没有意识到这一问题能引起群情激奋。
• The strike is growing in intensity.罢工日益加剧。

61 dilute   

vt.稀释，冲淡；adj.稀释的，冲淡的

参考例句：

• The water will dilute the wine.水能使酒变淡。
• Zinc displaces the hydrogen of dilute acids.锌置换了稀酸中的氢。

62 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

63 partially   

adv.部分地，从某些方面讲

参考例句：

• The door was partially concealed by the drapes.门有一部分被门帘遮住了。
• The police managed to restore calm and the curfew was partially lifted.警方设法恢复了平静，宵禁部分解除。

64 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

65 zinc   

n.锌；vt.在...上镀锌

参考例句：

• Brass is formed by the fusion of copper and zinc.黄铜是通过铜和锌的熔合而成的。
• Zinc is used to protect other metals from corrosion.锌被用来保护其他金属不受腐蚀。

66 copper   

n.铜；铜币；铜器；adj.铜(制)的；(紫)铜色的

参考例句：

• The students are asked to prove the purity of copper.要求学生们检验铜的纯度。
• Copper is a good medium for the conduction of heat and electricity.铜是热和电的良导体。

67 metallic   

adj.金属的；金属制的；含金属的；产金属的；像金属的

参考例句：

• A sharp metallic note coming from the outside frightened me.外面传来尖锐铿锵的声音吓了我一跳。
• He picked up a metallic ring last night.昨夜他捡了一个金属戒指。

68 poised   

a.摆好姿势不动的

参考例句：

• The hawk poised in mid-air ready to swoop. 老鹰在半空中盘旋，准备俯冲。
• Tina was tense, her hand poised over the telephone. 蒂娜心情紧张，手悬在电话机上。

69 deflected   

偏离的

参考例句：

• The ball deflected off Reid's body into the goal. 球打在里德身上反弹进球门。
• Most of its particles are deflected. 此物质的料子大多是偏斜的。

70 deflect   

v.(使)偏斜，(使)偏离，(使)转向

参考例句：

• Never let a little problem deflect you.决不要因一点小问题就半途而废。
• They decided to deflect from the original plan.他们决定改变原计划。

71 intensified   

v.（使）增强， （使）加剧( intensify的过去式和过去分词 )

参考例句：

• Violence intensified during the night. 在夜间暴力活动加剧了。
• The drought has intensified. 旱情加剧了。 来自《简明英汉词典》

72 conspire   

v.密谋，（事件等）巧合，共同导致

参考例句：

• They'd conspired to overthrow the government.他们曾经密谋推翻政府。
• History and geography have conspired to bring Greece to a moment of decision.历史和地理因素共同将希腊推至作出抉择的紧要关头。

73 sufficiently   

adv.足够地，充分地

参考例句：

• It turned out he had not insured the house sufficiently.原来他没有给房屋投足保险。
• The new policy was sufficiently elastic to accommodate both views.新政策充分灵活地适用两种观点。

74 vertically   

adv.垂直地

参考例句：

• Line the pages for the graph both horizontally and vertically.在这几页上同时画上横线和竖线，以便制作图表。
• The human brain is divided vertically down the middle into two hemispheres.人脑从中央垂直地分为两半球。

75 vertical   

adj.垂直的，顶点的，纵向的；n.垂直物，垂直的位置

参考例句：

• The northern side of the mountain is almost vertical.这座山的北坡几乎是垂直的。
• Vertical air motions are not measured by this system.垂直气流的运动不用这种系统来测量。

76 axis   

n.轴，轴线，中心线；坐标轴，基准线

参考例句：

• The earth's axis is the line between the North and South Poles.地轴是南北极之间的线。
• The axis of a circle is its diameter.圆的轴线是其直径。

77 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

78 simultaneously   

adv.同时发生地，同时进行地

参考例句：

• The radar beam can track a number of targets almost simultaneously.雷达波几乎可以同时追着多个目标。
• The Windows allow a computer user to execute multiple programs simultaneously.Windows允许计算机用户同时运行多个程序。

79 mechanism   

n.机械装置；机构，结构

参考例句：

• The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
• The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。

80 secondly   

adv.第二，其次

参考例句：

• Secondly,use your own head and present your point of view.第二，动脑筋提出自己的见解。
• Secondly it is necessary to define the applied load.其次，需要确定所作用的载荷。

81 figs   

figures 数字，图形，外形

参考例句：

• The effect of ring dyeing is shown in Figs 10 and 11. 环形染色的影响如图10和图11所示。
• The results in Figs. 4 and 5 show the excellent agreement between simulation and experiment. 图4和图5的结果都表明模拟和实验是相当吻合的。

82 dispensed   

v.分配( dispense的过去式和过去分词 )；施与；配（药）

参考例句：

• Not a single one of these conditions can be dispensed with. 这些条件缺一不可。 来自《现代汉英综合大词典》
• They dispensed new clothes to the children in the orphanage. 他们把新衣服发给孤儿院的小孩们。 来自《现代英汉综合大词典》

83 synchronously   

ad.同时地

参考例句：

• Both numbers may slide synchronously in opposite directions. 两数可以同步地向相反方向移位。
• The strong suction motor can synchronously pump the water. 双刷盘设计，清洗效果更强，强劲吸水电机同步抽走污水。

84 synchronous   

adj.同步的

参考例句：

• The message can be used only with synchronous operations.消息只能与同步操作一起使用。
• Synchronous machines do not easily fall out of step under normal conditions.在正常情况下，同步电机不易失去同步。

85 recording   

n.录音，记录

参考例句：

• How long will the recording of the song take?录下这首歌得花多少时间？
• I want to play you a recording of the rehearsal.我想给你放一下彩排的录像。

86 acting   

n.演戏，行为，假装；adj.代理的，临时的，演出用的

参考例句：

• Ignore her,she's just acting.别理她，她只是假装的。
• During the seventies,her acting career was in eclipse.在七十年代，她的表演生涯黯然失色。

87 auxiliary   

adj.辅助的，备用的

参考例句：

• I work in an auxiliary unit.我在一家附属单位工作。
• The hospital has an auxiliary power system in case of blackout.这家医院装有备用发电系统以防灯火管制。

88 neutralizes   

v.使失效( neutralize的第三人称单数 )；抵消；中和；使（一个国家）中立化

参考例句：

• The dendrimer locks onto toxins and neutralizes them. 树状物锁在毒物表面，从而中和毒物。 来自英汉非文学 - 生命科学 - 预防生物武器
• A substance, such as magnesia or sodium bicarbonate, that neutralizes acid. 解酸的，抗酸的，防酸的，中和酸的消除或中和酸度的，尤其胃酸。 来自互联网

89 deflects   

（使）偏斜， （使）偏离， （使）转向( deflect的第三人称单数 )

参考例句：

• This love is so bright that it deflects all darkness. 这个爱如此光明而可以照亮黑暗。
• Level 3-Deflects 15% of damage taken onto a 600 AoE. 三级-将15%的所受伤害反弹给600范围内的所有敌方单位。

90 neutralizing   

v.使失效( neutralize的现在分词 )；抵消；中和；使（一个国家）中立化

参考例句：

• This juice-about a quart a day--pours into my duodenum, neutralizing acids. 这种消化液（每天约分泌1品脱）流入我的十二指肠，把酸中和了。 来自辞典例句
• AIM: To verify the role of a synthetic peptide in neutralizing endotoxins. 目的：检验一条合成肽在中和内毒素活性方面的作用。 来自互联网

91 compensate   

vt.补偿，赔偿；酬报 vi.弥补；补偿；抵消

参考例句：

• She used her good looks to compensate her lack of intelligence. 她利用她漂亮的外表来弥补智力的不足。
• Nothing can compensate for the loss of one's health. 一个人失去了键康是不可弥补的。

92 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

93 sheathing   

n.覆盖物，罩子v.将（刀、剑等）插入鞘( sheathe的现在分词 )；包，覆盖

参考例句：

• The effect of nitrogen can be overcome by sheathing the flame in argon. 氮的影响则可以通过用氩气包覆火焰而予以克服。 来自辞典例句
• Sheathing layer: PVC extruded polyethylene or in the form of weaving. 护套层：用聚乙烯或聚氯乙烯挤塑在编织层上而成的。 来自互联网

94 exterior   

adj.外部的，外在的；表面的

参考例句：

• The seed has a hard exterior covering.这种子外壳很硬。
• We are painting the exterior wall of the house.我们正在给房子的外墙涂漆。

95 condenser   

n.冷凝器；电容器

参考例句：

• Their common principle is to use the variable capacity in a condenser.它们的普遍原理是利用电容器的可变电容。
• Steam is condensed in the condenser.蒸汽在冷凝器中凝结。

96 retardation   

n.智力迟钝，精神发育迟缓

参考例句：

• Asbestos reinforcement confers excellent flame retardation properties on a composite. 石棉增强材料使复合材料具有优异的防火性能。
• The theory confirms the increase in the retardation effect with decrease in particle size. 理论证实，随着颗粒尺寸的减小，这一减速效应将增大。

97 velocity   

n.速度，速率

参考例句：

• Einstein's theory links energy with mass and velocity of light.爱因斯坦的理论把能量同质量和光速联系起来。
• The velocity of light is about 300000 kilometres per second.光速约为每秒300000公里。

98 attain   

vt.达到，获得，完成

参考例句：

• I used the scientific method to attain this end. 我用科学的方法来达到这一目的。
• His painstaking to attain his goal in life is praiseworthy. 他为实现人生目标所下的苦功是值得称赞的。

99 interval   

n.间隔，间距；幕间休息，中场休息

参考例句：

• The interval between the two trees measures 40 feet.这两棵树的间隔是40英尺。
• There was a long interval before he anwsered the telephone.隔了好久他才回了电话。

100 intervals   

n.[军事]间隔( interval的名词复数 )；间隔时间；[数学]区间；（戏剧、电影或音乐会的）幕间休息

参考例句：

• The forecast said there would be sunny intervals and showers. 预报间晴，有阵雨。
• Meetings take place at fortnightly intervals. 每两周开一次会。

101 subsides   

v.（土地）下陷（因在地下采矿）( subside的第三人称单数 )；减弱；下降至较低或正常水平；一下子坐在椅子等上

参考例句：

• Emotion swells and subsides. 情绪忽高忽低。 来自《现代汉英综合大词典》
• His emotion swells and subsides. 他的情绪忽高忽低。 来自《现代英汉综合大词典》

102 reverting   

恢复( revert的现在分词 )； 重提； 回到…上； 归还

参考例句：

• The boss came back from holiday all relaxed and smiling, but now he's reverting to type. 老板刚度假回来时十分随和，满面笑容，现在又恢复原样了。
• The conversation kept reverting to the subject of money. 谈话的内容总是离不开钱的事。

103 derived   

vi.起源；由来；衍生；导出v.得到( derive的过去式和过去分词 )；（从…中）得到获得；源于；（从…中）提取

参考例句：

• Many English words are derived from Latin and Greek. 英语很多词源出于拉丁文和希腊文。 来自《简明英汉词典》
• He derived his enthusiasm for literature from his father. 他对文学的爱好是受他父亲的影响。 来自《简明英汉词典》

104 condensers   

n.冷凝器( condenser的名词复数 )；（尤指汽车发动机内的）电容器

参考例句：

• This is an area where dynamics and condensers are used about equally. 这是一个动圈麦和电容麦差不多都同被使用到的区域。 来自互联网
• All condensers work by removing heat from the gas or vapour. 所有的冷凝器都是把气体或蒸汽的热量带走而运转的。 来自互联网

105 requisites   

n.必要的事物( requisite的名词复数 )

参考例句：

• It is obvious that there are two requisites. 显然有两个必要部分。 来自辞典例句
• Capacity of donor is one of the essential requisites of \"gift\". 赠与人的行为能力是\"赠与\"的一个重要前提。 来自口语例句

106 standing   

n.持续，地位；adj.永久的，不动的，直立的，不流动的

参考例句：

• After the earthquake only a few houses were left standing.地震过后只有几幢房屋还立着。
• They're standing out against any change in the law.他们坚决反对对法律做任何修改。

107 interfered   

v.干预( interfere的过去式和过去分词 )；调停；妨碍；干涉

参考例句：

• Complete absorption in sports interfered with his studies. 专注于运动妨碍了他的学业。 来自《简明英汉词典》
• I am not going to be interfered with. 我不想别人干扰我的事情。 来自《简明英汉词典》

108 proprietors   

n.所有人，业主( proprietor的名词复数 )

参考例句：

• These little proprietors of businesses are lords indeed on their own ground. 这些小业主们，在他们自己的行当中，就是真正的至高无上的统治者。 来自英汉文学 - 嘉莉妹妹
• Many proprietors try to furnish their hotels with antiques. 许多经营者都想用古董装饰他们的酒店。 来自辞典例句

109 deflecting   

（使）偏斜， （使）偏离， （使）转向( deflect的现在分词 )

参考例句：

• A variety of mechanical surfaces have been employed for deflecting the exhaust jets of solid-propellant rockets. 人们已经用过各种类型的机械控制面来偏转固体推进剂火箭的排气流。
• If she made a leading statement, he was expert deflecting her into more impersonal channels. 只要她一开口，他就会巧妙地把她的话题转到与个人无关的问题上去。

110 bent   

n.爱好，癖好；adj.弯的；决心的，一心的

参考例句：

• He was fully bent upon the project.他一心扑在这项计划上。
• We bent over backward to help them.我们尽了最大努力帮助他们。

111 descending   

n. 下行 adj. 下降的

参考例句：

• The results are expressed in descending numerical order . 结果按数字降序列出。
• The climbers stopped to orient themselves before descending the mountain. 登山者先停下来确定所在的位置，然后再下山。

112 modifications   

n.缓和( modification的名词复数 )；限制；更改；改变

参考例句：

• The engine was pulled apart for modifications and then reassembled. 发动机被拆开改型，然后再组装起来。 来自《简明英汉词典》
• The original plan had undergone fairly extensive modifications. 原计划已经作了相当大的修改。 来自《简明英汉词典》

113 pointed   

adj.尖的，直截了当的

参考例句：

• He gave me a very sharp pointed pencil.他给我一支削得非常尖的铅笔。
• She wished to show Mrs.John Dashwood by this pointed invitation to her brother.她想通过对达茨伍德夫人提出直截了当的邀请向她的哥哥表示出来。

114 steadily   

adv.稳定地；不变地；持续地

参考例句：

• The scope of man's use of natural resources will steadily grow.人类利用自然资源的广度将日益扩大。
• Our educational reform was steadily led onto the correct path.我们的教学改革慢慢上轨道了。

115 elongated   

v.延长，加长( elongate的过去式和过去分词 )

参考例句：

• Modigliani's women have strangely elongated faces. 莫迪里阿尼画中的妇女都长着奇长无比的脸。
• A piece of rubber can be elongated by streching. 一块橡皮可以拉长。 来自《用法词典》

116 thwart   

v.阻挠，妨碍，反对；adj.横(断的)

参考例句：

• We must thwart his malevolent schemes.我们决不能让他的恶毒阴谋得逞。
• I don't think that will thwart our purposes.我认为那不会使我们的目的受到挫折。

117 pendulum   

n.摆，钟摆

参考例句：

• The pendulum swung slowly to and fro.钟摆在慢慢地来回摆动。
• He accidentally found that the desk clock did not swing its pendulum.他无意中发现座钟不摇摆了。

118 cylindrical   

adj.圆筒形的

参考例句：

• huge cylindrical gas tanks 巨大的圆柱形贮气罐
• Beer cans are cylindrical. 啤酒罐子是圆筒形的。

119 nay   

adv.不；n.反对票，投反对票者

参考例句：

• He was grateful for and proud of his son's remarkable,nay,unique performance.他为儿子出色的，不，应该是独一无二的表演心怀感激和骄傲。
• Long essays,nay,whole books have been written on this.许多长篇大论的文章，不，应该说是整部整部的书都是关于这件事的。

120 notation   

n.记号法，表示法，注释；[计算机]记法

参考例句：

• Music has a special system of notation.音乐有一套特殊的标记法。
• We shall find it convenient to adopt the following notation.采用下面的记号是方便的。

121 cylinder   

n.圆筒，柱(面)，汽缸

参考例句：

• What's the volume of this cylinder?这个圆筒的体积有多少？
• The cylinder is getting too much gas and not enough air.汽缸里汽油太多而空气不足。

122 accomplished   

adj.有才艺的；有造诣的；达到了的

参考例句：

• Thanks to your help,we accomplished the task ahead of schedule.亏得你们帮忙,我们才提前完成了任务。
• Removal of excess heat is accomplished by means of a radiator.通过散热器完成多余热量的排出。

123 despatch   

n./v.(dispatch)派遣；发送；n.急件；新闻报道

参考例句：

• The despatch of the task force is purely a contingency measure.派出特遣部队纯粹是应急之举。
• He rushed the despatch through to headquarters.他把急件赶送到总部。

124 apparatus   

n.装置，器械；器具，设备

参考例句：

• The school's audio apparatus includes films and records.学校的视听设备包括放映机和录音机。
• They had a very refined apparatus.他们有一套非常精良的设备。

125 absconder   

n.潜逃者，逃跑者

参考例句：

126 deserted   

adj.荒芜的，荒废的，无人的，被遗弃的

参考例句：

• The deserted village was filled with a deathly silence.这个荒废的村庄死一般的寂静。
• The enemy chieftain was opposed and deserted by his followers.敌人头目众叛亲离。

127 likeness   

n.相像，相似（之处）

参考例句：

• I think the painter has produced a very true likeness.我认为这位画家画得非常逼真。
• She treasured the painted likeness of her son.她珍藏她儿子的画像。

128 tune   

n.调子；和谐，协调；v.调音，调节，调整

参考例句：

• He'd written a tune,and played it to us on the piano.他写了一段曲子，并在钢琴上弹给我们听。
• The boy beat out a tune on a tin can.那男孩在易拉罐上敲出一首曲子。

129 tunes   

n.曲调，曲子( tune的名词复数 )v.调音( tune的第三人称单数 )；调整；（给收音机、电视等）调谐；使协调

参考例句：

• a potpourri of tunes 乐曲集锦
• When things get a bit too much, she simply tunes out temporarily. 碰到事情太棘手时，她干脆暂时撒手不管。 来自《简明英汉词典》

130 anticipation   

n.预期，预料，期望

参考例句：

• We waited at the station in anticipation of her arrival.我们在车站等着，期待她的到来。
• The animals grew restless as if in anticipation of an earthquake.各种动物都变得焦躁不安，像是感到了地震即将发生。

131 indicator   

n.指标；指示物，指示者；指示器

参考例句：

• Gold prices are often seen as an indicator of inflation.黃金价格常常被看作是通货膨胀的指标。
• His left-hand indicator is flashing.他左手边的转向灯正在闪亮。

132 perfectly   

adv.完美地，无可非议地，彻底地

参考例句：

• The witnesses were each perfectly certain of what they said.证人们个个对自己所说的话十分肯定。
• Everything that we're doing is all perfectly above board.我们做的每件事情都是光明正大的。

133 skilful   

(=skillful)adj.灵巧的，熟练的

参考例句：

• The more you practise,the more skilful you'll become.练习的次数越多，熟练的程度越高。
• He's not very skilful with his chopsticks.他用筷子不大熟练。

134 regiment   

n.团，多数，管理；v.组织，编成团，统制

参考例句：

• As he hated army life,he decide to desert his regiment.因为他嫌恶军队生活，所以他决心背弃自己所在的那个团。
• They reformed a division into a regiment.他们将一个师整编成为一个团。

135 membrane   

n.薄膜，膜皮，羊皮纸

参考例句：

• A vibrating membrane in the ear helps to convey sounds to the brain.耳膜的振动帮助声音传送到大脑。
• A plastic membrane serves as selective diffusion barrier.一层塑料薄膜起着选择性渗透屏障的作用。

136 vibrations   

n.摆动( vibration的名词复数 )；震动；感受；（偏离平衡位置的）一次性往复振动

参考例句：

• We could feel the vibrations from the trucks passing outside. 我们可以感到外面卡车经过时的颤动。
• I am drawn to that girl; I get good vibrations from her. 我被那女孩吸引住了，她使我产生良好的感觉。 来自《简明英汉词典》

137 vibration   

n.颤动，振动；摆动

参考例句：

• There is so much vibration on a ship that one cannot write.船上的震动大得使人无法书写。
• The vibration of the window woke me up.窗子的震动把我惊醒了。

138 synchronizing   

v.同步，整步adj.同步的

参考例句：

• How to monitoring synchronizing error, and using 80196KC to control exciter. 以及同步电动机失步检测及以80196KC进行控制的方法。 来自互联网
• A synchronizing labyrinth must be created at a special, predetermined place. 同步迷宫必须建立在一个特殊的，预先确定的地方。 来自互联网

139 infancy   

n.婴儿期；幼年期；初期

参考例句：

• He came to England in his infancy.他幼年时期来到英国。
• Their research is only in its infancy.他们的研究处于初级阶段。

140 situated   

adj.坐落在...的，处于某种境地的

参考例句：

• The village is situated at the margin of a forest.村子位于森林的边缘。
• She is awkwardly situated.她的处境困难。

141 polytechnic   

adj.各种工艺的，综合技术的；n.工艺(专科)学校；理工(专科)学校

参考例句：

• She was trained as a teacher at Manchester Polytechnic.她在曼彻斯特工艺专科学校就读，准备毕业后做老师。
• When he was 17,Einstein entered the Polytechnic Zurich,Switzerland,where he studied mathematics and physics.17岁时，爱因斯坦进入了瑞士苏黎士的专科学院，学习数学和物理学。

142 extremity   

n.末端，尽头；尽力；终极；极度

参考例句：

• I hope you will help them in their extremity.我希望你能帮助在穷途末路的他们。
• What shall we do in this extremity?在这种极其困难的情况下我们该怎么办呢？

143 advancement   

n.前进，促进，提升

参考例句：

• His new contribution to the advancement of physiology was well appreciated.他对生理学发展的新贡献获得高度赞赏。
• The aim of a university should be the advancement of learning.大学的目标应是促进学术。

144 undoubtedly   

adv.确实地，无疑地

参考例句：

• It is undoubtedly she who has said that.这话明明是她说的。
• He is undoubtedly the pride of China.毫无疑问他是中国的骄傲。

145 touching   

adj.动人的，使人感伤的

参考例句：

• It was a touching sight.这是一幅动人的景象。
• His letter was touching.他的信很感人。

146 intermittent   

adj.间歇的，断断续续的

参考例句：

• Did you hear the intermittent sound outside?你听见外面时断时续的声音了吗？
• In the daytime intermittent rains freshened all the earth.白天里，时断时续地下着雨，使整个大地都生气勃勃了。

147 lengthening   

（时间或空间）延长，伸长( lengthen的现在分词 )； 加长

参考例句：

• The evening shadows were lengthening. 残阳下的影子越拉越长。
• The shadows are lengthening for me. 我的影子越来越长了。 来自演讲部分

148 capabilities   

n.能力( capability的名词复数 )；可能；容量；[复数]潜在能力

参考例句：

• He was somewhat pompous and had a high opinion of his own capabilities. 他有点自大，自视甚高。 来自辞典例句
• Some programmers use tabs to break complex product capabilities into smaller chunks. 一些程序员认为，标签可以将复杂的功能分为每个窗格一组简单的功能。 来自About Face 3交互设计精髓

149 enthusiasts   

n.热心人，热衷者( enthusiast的名词复数 )

参考例句：

• A group of enthusiasts have undertaken the reconstruction of a steam locomotive. 一群火车迷已担负起重造蒸汽机车的任务。 来自《简明英汉词典》
• Now a group of enthusiasts are going to have the plane restored. 一群热心人计划修复这架飞机。 来自新概念英语第二册

150 leakage   

n.漏，泄漏；泄漏物；漏出量

参考例句：

• Large areas of land have been contaminated by the leakage from the nuclear reactor.大片地区都被核反应堆的泄漏物污染了。
• The continuing leakage is the result of the long crack in the pipe.这根管子上的那一条裂缝致使渗漏不断。

151 rosy   

adj.美好的，乐观的，玫瑰色的

参考例句：

• She got a new job and her life looks rosy.她找到一份新工作，生活看上去很美好。
• She always takes a rosy view of life.她总是对生活持乐观态度。

152 exalted   

adj.(地位等)高的，崇高的；尊贵的，高尚的

参考例句：

• Their loveliness and holiness in accordance with their exalted station.他们的美丽和圣洁也与他们的崇高地位相称。
• He received respect because he was a person of exalted rank.他因为是个地位崇高的人而受到尊敬。

153 vocal   

adj.直言不讳的；嗓音的；n.[pl.]声乐节目

参考例句：

• The tongue is a vocal organ.舌头是一个发音器官。
• Public opinion at last became vocal.终于舆论哗然。

154 amplitude   

n.广大；充足；振幅

参考例句：

• The amplitude of the vibration determines the loudness of the sound.振动幅度的大小决定声音的大小。
• The amplitude at the driven end is fixed by the driving mechanism.由于驱动机构的作用,使驱动端的振幅保持不变。

155 varied   

adj.多样的，多变化的

参考例句：

• The forms of art are many and varied.艺术的形式是多种多样的。
• The hotel has a varied programme of nightly entertainment.宾馆有各种晚间娱乐活动。

156 articulation   

n.（清楚的）发音；清晰度，咬合

参考例句：

• His articulation is poor.他发音不清楚。
• She spoke with a lazy articulation.她说话慢吞吞的。

157 random   

adj.随机的；任意的；n.偶然的(或随便的)行动

参考例句：

• The list is arranged in a random order.名单排列不分先后。
• On random inspection the meat was found to be bad.经抽查，发现肉变质了。

158 delicacies   

n.棘手( delicacy的名词复数 )；精致；精美的食物；周到

参考例句：

• Its flesh has exceptional delicacies. 它的肉异常鲜美。 来自《现代汉英综合大词典》
• After these delicacies, the trappers were ready for their feast. 在享用了这些美食之后，狩猎者开始其大餐。 来自英汉非文学 - 民俗

159 permanently   

adv.永恒地，永久地，固定不变地

参考例句：

• The accident left him permanently scarred.那次事故给他留下了永久的伤疤。
• The ship is now permanently moored on the Thames in London.该船现在永久地停泊在伦敦泰晤士河边。

160 virtue   

n.德行，美德；贞操；优点；功效，效力

参考例句：

• He was considered to be a paragon of virtue.他被认为是品德尽善尽美的典范。
• You need to decorate your mind with virtue.你应该用德行美化心灵。

161 converge   

vi.会合；聚集，集中；(思想、观点等)趋近

参考例句：

• The results converge towards this truth.其结果趋近于这个真理。
• Parallel lines converge at infinity.平行线永不相交。

162 proximity   

n.接近，邻近

参考例句：

• Marriages in proximity of blood are forbidden by the law.法律规定禁止近亲结婚。
• Their house is in close proximity to ours.他们的房子很接近我们的。

163 distinguished   

adj.卓越的，杰出的，著名的

参考例句：

• Elephants are distinguished from other animals by their long noses.大象以其长长的鼻子显示出与其他动物的不同。
• A banquet was given in honor of the distinguished guests.宴会是为了向贵宾们致敬而举行的。

164 strand   

vt.使（船）搁浅，使（某人）困于（某地）

参考例句：

• She tucked a loose strand of hair behind her ears.她把一缕散发夹到了耳后。
• The climbers had been stranded by a storm.登山者被暴风雨困住了。

165 culminated   

v.达到极点( culminate的过去式和过去分词 )

参考例句：

• a gun battle which culminated in the death of two police officers 一场造成两名警察死亡的枪战
• The gala culminated in a firework display. 晚会以大放烟火告终。 来自《简明英汉词典》

166 promising   

adj.有希望的，有前途的

参考例句：

• The results of the experiments are very promising.实验的结果充满了希望。
• We're trying to bring along one or two promising young swimmers.我们正设法培养出一两名有前途的年轻游泳选手。

167 platinum   

n.白金

参考例句：

• I'll give her a platinum ring.我打算送给她一枚白金戒指。
• Platinum exceeds gold in value.白金的价值高于黄金。

168 outwards   

adj.外面的，公开的，向外的；adv.向外；n.外形

参考例句：

• Does this door open inwards or outwards?这门朝里开还是朝外开？
• In lapping up a fur,they always put the inner side outwards.卷毛皮时，他们总是让内层朝外。

169 bass   

n.男低音(歌手)；低音乐器；低音大提琴

参考例句：

• He answered my question in a surprisingly deep bass.他用一种低得出奇的声音回答我的问题。
• The bass was to give a concert in the park.那位男低音歌唱家将在公园中举行音乐会。

170 delicacy   

n.精致，细微，微妙，精良；美味，佳肴

参考例句：

• We admired the delicacy of the craftsmanship.我们佩服工艺师精巧的手艺。
• He sensed the delicacy of the situation.他感觉到了形势的微妙。

171 astronomical   

adj.天文学的，（数字）极大的

参考例句：

• He was an expert on ancient Chinese astronomical literature.他是研究中国古代天文学文献的专家。
• Houses in the village are selling for astronomical prices.乡村的房价正在飙升。

172 tilt   

v.(使)倾侧；(使)倾斜；n.倾侧；倾斜

参考例句：

• She wore her hat at a tilt over her left eye.她歪戴着帽子遮住左眼。
• The table is at a slight tilt.这张桌子没放平，有点儿歪.

173 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪，为什么只有土星有光环。 来自《简明英汉词典》

174 buoy   

n.浮标；救生圈；v.支持，鼓励

参考例句：

• The party did little to buoy up her spirits.这次聚会并没有让她振作多少。
• The buoy floated back and forth in the shallow water.这个浮标在浅水里漂来漂去。

175 thumping   

adj.重大的，巨大的；重击的；尺码大的；极好的adv.极端地；非常地v.重击(thump的现在分词)；狠打；怦怦地跳；全力支持

参考例句：

• Her heart was thumping with emotion. 她激动得心怦怦直跳。 来自《现代汉英综合大词典》
• He was thumping the keys of the piano. 他用力弹钢琴。 来自《现代英汉综合大词典》