In reality, the story of the discovery of the steam engine is far more inspiring. The history of the application of steam to human use is almost the history of science itself; the stages of its development are clearly marked for us; and the large succession of these stages, and the calibre of the minds which contributed to the achievement of the perfected steam engine, are some measure of the essential complexity8 of what is to-day regarded as a comparatively simple machine. For the steam engine was not the gift of any particular genius or generation; it did not leap from any one man’s brain. Some of the greatest names in the history of human knowledge can claim a share in its discovery. From philosopher to scientist, from scientist to94 engineer the grand idea was carried on, gradually taking more and more concrete form, until finally, in an age when by the diffusion9 of knowledge the labours of all three were for the first time co-ordinated, it was brought to maturity10. A new force of nature was harnessed which wrought11 a revolution in the civilized12 world.
An attempt is made in this chapter to chronicle the circumstances under which the successive developments of the steam engine took place. The progress of the scientific ideas which led up to the discovery of the power of steam is traced. The claims of the various inventors chiefly associated with the steam engine are set forth13 in some detail, not for the difficult and invidious task of assessing their relative merits, but because by the light of these claims and altercations14 it may be possible to discern, in each case, where the merit lay and to what stage each novelty of idea or detail properly belonged. From this point of view, it is thought, the recital15 of circumstances which hitherto have been thought so trivial as to be scarcely worthy16 of record, may be of some suggestive value. The result of the investigation17 is to make clear the scientific importance of the steam engine: the steam engine regarded, not as the familiar drudge18 and commonplace servant of to-day, but in all its dignity of a thermodynamic machine, that scientific device which embodied19 so much of the natural philosophy of the age which first unveiled it—the seventeenth century.
§
Before the Christian20 era steam had been used to do mechanical work. In a treatise21, Pneumatica, written by Hero of Alexandria about 130 B.C., mention is made of a primitive22 reaction turbine, which functioned by the reactionary23 force of steam jets thrown off tangentially24 from the periphery25 of a wheel. In the same work another form of heat-engine is described: an apparatus26 in which, by the expansion from heating of air contained in a spherical27 vessel28, water was expelled from the same vessel to a bucket, where by its weight it gave motion mysteriously to the doors of temples. And evidence exists that in these two forms heat engines were used in later centuries for such trivial purposes as the blowing of organs and the turning of spits. But except in these two primitive forms no progress is recorded for seventeen centuries95 after the date of Hero’s book. The story of the evolution of steam as a motive29 force really begins, with the story of modern science itself, at the end of the Middle Ages.
With the great revival30 of learning which took place in Southern Europe in the latter part of the fifteenth century new light came to be thrown on the classical philosophies which still ruled men’s minds, and modern science was born. New views on natural phenomena31 began to irradiate, and, sweeping32 aside the myths and traditions which surrounded and stifled33 them, the votaries34 of the “new science” began to formulate35 opinions of the boldest and most unorthodox description.70 The true laws of the equilibrium36 of fluids, discovered originally by Archimedes, were rediscovered by Stevinus. By the end of the sixteenth century the nature of the physical universe was become a pursuit of the wisest men. To Galileo himself was due, perhaps, the first distinct conception of the power of steam or any other gas to do mechanical work; for “he, the Archimedes of his age, first clearly grasped the idea of force as a mechanical agent, and extended to the external world the conception of the invariability of the relation between cause and effect.”71 To his brilliant pupil Torricelli the questioning world was indebted for the experiments which showed the true nature of the atmosphere, and for the theory he proclaimed that the atmosphere by its own weight exerted its fluid pressure—a theory which Pascal soon confirmed by the famous ascent37 of his barometer38 up the Puy-de-D?me, which demonstrated that the pressure supporting his column of mercury grew less as the ascent proceeded. Giovanni della Porta, in a treatise on pneumatics published in the year 1601, had already made two suggestions of the first importance. Discussing Hero’s door-opening apparatus, della Porta showed that steam might be substituted for air as the expanding medium, and that, by condensing steam in a closed vessel, water might be sucked up from a lower level by virtue39 of the vacuum so formed. And a few years later, in 1615, Solomon de Caus, a French engineer, had come to England with a scheme almost identical with della Porta’s, and actually constructed a plant which forced up water to a height by means of steam. Shortly afterwards the “new science” received an accession of interest from the invention, by Otto von Guericke of Magdeburg, of a suction96 pump by which the atmospheric40 air could be abstracted from a closed vessel.
By the middle of this century the learned of all European countries had been attracted by the knowledge gained of the material universe. In England the secrets of science were attacked with enthusiasm under the new strategy of Lord Bacon, enunciated41 in his Novum Organum. The new philosophy was patronised by royalty42 itself, and studied by a company of brilliant men of whom the leading physicist43 was Robert Boyle, soon famous for his law connecting the volumes and the pressures of gases. In France, too, a great enthusiasm for science took birth. A group of men, of whom the most eminent44 was Christian Huyghens, banded themselves together to further scientific inquiry45 into the phenomena of nature and to demolish46 the reigning47 myths and fallacies: they also working admittedly by the experimental method of Bacon.
The time was ripe, however, for wider recognition of these scientists and the grand object of their labours. Within a short time the two groups were both given the charter of their respective countries; in France they were enrolled48 as the Royal Academy of Sciences; in England, as the Royal Society for Improving Natural Knowledge. In other countries societies of a similar kind were formed, but their influence was not comparable with that exerted by the societies of London and Paris. Between these two a correspondence was started which afterwards developed into one of the most famous of publications: the Philosophical50 Transactions. In England, especially, the Royal Society served from its inception51 as a focus for all the great minds of the day, and in time brought together such men as Newton, Wren52, Hooke, Wallis, Boyle—not to mention his majesty53 King Charles himself; who, with the best intentions, could not always take seriously the speculations54 of the savants. “Gresham College he mightily55 laughed at,” noted56 Mr. Pepys in his diary for the first of February, 1663, “for spending time only in weighing of ayre, and doing nothing else since they sat.” A year later Pepys was himself admitted a member of the distinguished57 company, and found it “a most acceptable thing to hear their discourse58, and see their experiments, which were this day on fire, and how it goes out in a place where the air is not free, and sooner out in a place where the ayre is exhausted59, which they showed by an engine on purpose.”
97
§
In the year 1663, just after the formation of the Royal Society, a small book was published by the Marquis of Worcester, A Century of the Names and Scantlings of such Inventions as he had tried and perfected.
Of these inventions one, the sixty-eighth, is thus described:
“An admirable and most forcible way to drive up water by fire, not by drawing or sucking it upwards60, for that must be as the Philosopher calleth it, Intra sph?ram61 activitatis, which is but at such a distance. But this way hath no bounder, if the vessels62 be strong enough; for I have taken a piece of a whole cannon63, whereof the end was burst, and filled it three-quarters full of water, stopping and screwing up the broken end, as also the touch-hole; and making a constant fire under it, within twenty-four hours it burst and made a great crack. So that having a way to make my vessels, so that they are strengthened by the force within them, and the one to fill after the other; I have seen the water run like a constant fountain-stream forty foot high; one vessel of water rarified by fire driveth up forty of cold water. And a man that tends the work is but to turn two cocks, that one vessel of water being consumed, another begins to force and refill with cold water, and so successfully, the fire being tended and kept constant, which the selfsame person may likewise abundantly perform in the interim64 between the necessity of turning the said cocks.”
On this evidence the claim is made that the marquis was the original inventor of the steam engine. Is he at all entitled to the honour? The whole affair is still surrounded with mystery. It is known that he was an enthusiastic student of physical science, and that for years he had working for him a Dutch mechanic, Caspar Kaltoff; it seems certain that he actually made a water-pumping engine worked by steam, of whose value he was so impressed that he promised to leave the drawings of it to Gresham College and intended to have a model of it buried with him.72 But neither model nor drawings98 has ever yet been traced. And, considering the social influence of the inventor and the importance of the invention, the silence of his contemporaries on the discovery is strange and inexplicable65. He received a patent for some form of water-pumping engine. Distinguished visitors came to Vauxhall to see his engine at work. He numbered among his acquaintances Sir Jonas Moore, Sir Samuel Morland, Flamstead and Evelyn: probably Mr. Pepys, Sir W. Petty, and others of the group of eminent men of his time who were interested in natural science. Yet no trace of his inventions has come down to us. His Century was admittedly compiled from memory—“my former notes being lost”—and perhaps it was designedly obscure; science was at that time a hobby of the cultured few, and scientific men loved to mystify each other by the exhibition, without explanation, of paradoxes66 and toys of their own construction. The marquis, it will be agreed, left valuable hints to later investigators67. Whether his claim to have invented the steam engine is sufficiently68 substantiated69, we leave to the opinion of the interested reader, who will find most of the evidence on this subject in Dirck’s Life of the Marquis of Worcester.
The power of steam to drive water from a lower to a higher level had been shown by Solomon de Caus,73 who, in his work, Les Raisons des Forces Mouvantes, published in A.D. 1615, had described a hot-water fountain operated by heating water in a globe. In Van Etten’s Récreation Mathematique of 1629 was an experiment, described fifty years later by Nathaniel Nye in his Art of Gunnery as a “merry conceit,” showing how the force of steam could be used to discharge a cannon. As the century advanced the ornamental71 was gradually superseded73 by the utilitarian74; the usefulness of steam for draining fens75, pumping out mines, was realized; and applications for patents to cover the use of new and carefully guarded inventions began to appear.
99 Gunpowder as a medium was a strong competitor of steam. In 1661 King Charles granted to Sir Samuel Morland, his master of mechanics, “for the space of fourteen years, to have the sole making and use of a new invention of a certain engine lately found out and devised by him, for the raising of water out of any mines, pits, or other places, to any reasonable height, and by the force of air and powder conjointly.” What form the engine took is not known; whether the gunpowder was used to produce a gaseous76 pressure by which the work was done, or whether its function was to displace air and thus cause a vacuum as its gases cooled. In France, too, efforts were made at this time to produce a gunpowder engine. In 1678 a Jean de Hautefeuille raised water by gunpowder, but authorities differ as to whether he employed a piston77—which were then in use as applied78 to pumps—or whether he burned the powder so that the gases came in actual contact with the water. In the following year an important advance was made. Huyghens constructed an engine having a piston and cylinder79, in which gunpowder was used to form a vacuum, the atmospheric pressure providing the positive force to produce motion; and in 1680 he communicated to the Academy of Sciences a paper entitled, “A new motive power by means of gunpowder and air.”
But it was to his brilliant pupil, Denis Papin, that we are indebted for a further step in the materialization of the steam engine. Papin suggested the use of steam for gunpowder.
In 1680 Papin, who like Solomon de Caus had brought his scientific conceptions to England in the hope of their furtherance, was admitted on the recommendation of Boyle to a fellowship of the Royal Society. After a short absence he returned to London in ’84 and filled for a time the post of curator to the society, meeting, doubtless, in that capacity the leading scientists of the day and coming in touch with all the practical efforts of English inventors. During his stay here he worked with enthusiasm at the production of a prime mover, and when he left in ’87 for a mathematical professorship in Germany he continued there his researches and experienced repeated failures. In a paper published in ’88 he showed a clear conception of a reciprocating80 engine actuated by atmospheric pressure, and in ’90 he suggested for the first time the use of steam for forming the vacuum required. As water, he wrote, has elasticity81 when fire has changed it into100 vapour, and as cold will condense it again, it should be possible to make engines in which, by the use of heat, water would provide the vacuum which gunpowder had failed to give. This memorable83 announcement gave a clear direction to the future development of the heat engine. Steam was the medium best suited for utilizing84 the expansive power of heat generated by the combustion85 of fuel; steam was the medium which, by its expansive and contractile properties, could be made to impart a movement de va et vient to a piston. Though Papin did not succeed in putting his idea into practical form his conception was of great value, and he must be counted as one of the principal contributors to the early development of the steam engine. His life was an accumulation of apparent failures ending in abject86 poverty. To-day he is honoured by France as the inventor of the steam engine, and at Blois a statue has been erected87 and a street named to his memory.
Before the end of the century an effective engine had been produced, in England.
In 1698 Thomas Savery, a Devonshire man, obtained a patent for “a new invention for raising of water and occasioning motion to all sorts of millwork by the impellent force of fire.” Before the king at Hampton Court a model of this invention was displayed, and the importance of the new discovery was soon realized by the landed classes; for in the following year an act of parliament was passed for the encouragement of the inventor and for his protection in the development of what, it was recognized, was likely to prove of great use to the public. In the same year Savery published a pamphlet called The Miner’s Friend, and republished it, with additions, in 1702. This pamphlet contained a full and clear description of his engine; but significance has been attached to the omission89 from it of any claim that it embodied a new idea. The omission may be accidental.
The steam engine, shown in the accompanying illustration, was simply a pump, whose cycle of operations was as follows. Steam, admitted into the top of a closed vessel containing water and acting90 directly against the water, forced it through a pipe to a level higher than the vessel itself. Then, the vessel being chilled and the steam in it thereby91 condensed, more water was sucked into the vessel from a lower level to fill the vacuum thus formed; this water was expelled by steam in the same way as before, cocks being manipulated, and, eventually,101 self-acting valves being placed, so as to prevent the water from returning by the way it came. Two chambers92 were used, operating alternately.
For this achievement Savery is by many regarded as the first and true inventor. He certainly was the first to make the steam engine a commercial success, and up and down the country it was extensively used for pumping water and for draining mines. By others Savery was regarded as a copyist; and indeed it is difficult to say how far originality94 should be assigned him. The marquis too had claimed to raise water; his engine had evidently acted with a pair of displacement-chambers, from each of which alternately water was forced by steam while the other vessel was filling. And if he did not specify95 or appreciate the effect of the contractile force of the steam when condensed, yet in this respect both inventors had been anticipated by Giovanni della Porta.
Steam from Boiler96.
SAVERY’S ENGINE
The marquis had a violent champion in Dr. Desaguliers, who in his Experimental Philosophy, published in 1743, imputed97 disreputable conduct to the later inventor. “Captain Savery,” said the doctor, “having read the Marquis of Worcester’s book, was the first who put into practice the raising of water by fire. His engine will easily appear to have been taken from the Marquis of Worcester; though Captain Savery denied it, and the better to conceal98 the matter, bought all the Marquis of Worcester’s books that he could purchase in Pater-Noster Row and elsewhere, and burned them in the presence of the gentleman his friend, who told me this. He said that he found out the power of steam by chance, and invented the following story to persuade people to believe it, viz. that having drunk a flask99 of Florence at a tavern100, and thrown the empty flask upon the fire, he called for a bason of water to wash his hands, and perceiving that the little wine left in the flask had filled the flask with steam, he took the flask by the neck and plunged101 the mouth of it under the102 surface of the water in the bason, and the water in the bason was immediately driven up into the flask by the pressure of the air. Now, he never made such an experiment then, nor designedly afterwards, which I shall thus prove,” etc. etc.
Other writers saw no good reason for depriving the captain of the title of inventor. With reference to the book-burning allegation, the only evidence tending to substantiate70 it lay in the fact that the book “on a sudden became very scarce, and but few copies of it were afterwards seen, and then only in the libraries of the curious.”74 It has been remarked, also, that Desaguliers was himself to some extent a rival claimant, several improvements, such as the substitution of jet for the original surface condensation103 being due to him; and that this fact gave a palpable bias104 to his testimony105 on the work of others.
In recent years the claims of Savery have been upheld, as against those of the marquis, by a writer who argued, not only that the engine of the marquis had never passed the experimental stage, but that no counter-claim was made by his successors at the time Savery produced his engine and obtained his patent. “Although a patent for ninety-nine years (from 1663 to 1762) was granted the marquis, yet Captain Savery and his successors under his patents which extended for thirty-five years (from 1698 to 1733) compelled every user of Newcomen’s and other steam engines to submit to the most grinding terms and no one attempted to plead that Savery’s patents were invalidated by the Marquis of Worcester’s prior patents.”75
By the admirers of Papin it has been claimed that it was from him that Savery received his idea. “After having minutely compared Savery’s machine,” says a biographer of Papin, “one arrives at the conviction that Savery discovered nothing. He had borrowed from Solomon de Caus the use of steam as a motive force, perfected by the addition of a second chamber93; from Papin, the condensation of the steam.... And as for the piston, borrowed ten years later by Newcomen, that was wholly Papin’s.”76
Suppose it true; even so, his countrymen would always think great credit attaches to Savery for his achievement.
103 His engine, though used extensively for lifting water through small distances, was exceedingly wasteful106 of fuel, nor could it be used conveniently for pumping out mines or for other purposes in which a large lift was required. The lift or “head” was directly proportional to the steam pressure. Efforts to improve the lift by augmenting107 the steam pressure resulted in endless accidents and discouragement; the solder108 of the engine melted when steam of a higher pressure was used, the joints109 blew open and the chambers burst.
Living at Dartmouth, within some fifteen miles of Savery’s home, were two men, Newcomen, an ironmonger, and Cawley, a glazier. These two had, doubtless, every opportunity of seeing Savery’s engine at work. They appreciated its limitations and defects, and, undertaking110 the task of improving it, they so transformed the steam engine that within a short time their design had almost entirely111 superseded the more primitive form. Here, too, it might be said that they invented nothing. The merit of their new machine consisted in the achievement in practical form of ideas which hitherto had had scarcely more than an academic value. The labours of others gave them valuable aid. Newcomen, it is certain, could claim considerable knowledge of science, and though little is known of his personality there is evidence that he had pursued for years the object which he now achieved. He knew of the previous forms of piston engine which had been invented. He had probably read a translation, published in the Philosophical Transactions, of Papin’s proposal for an atmospheric engine with a vacuum produced by the condensation of steam. He obtained from Savery the idea of a separate boiler, and other details. And where Papin had failed, Newcomen and his partner succeeded. Their Atmospheric Steam Engine, as it was aptly called, was produced in the year 1705, and at once proved its superiority over the old “Miner’s Friend.” It had assumed an entirely new form. In a large-bore vertical112 cylinder a brass113 piston was fitted, with a leather flap round its edge and a layer of water standing114 on it to form a seal against the passage of steam or air. The top of the cylinder was open to the atmosphere, the bottom was connected by a pipe with a spherical boiler. The piston was suspended by a chain to one end of an overhanging timber beam, which was mounted on a brick structure so as to be capable of oscillating on a gudgeon or axis115 at its middle. One end of this beam was104 vertically116 over the piston; at the other end was the bucket of a water-pump, also attached to a crosspiece or “horse-head,” by means of a chain or rod. The whole machine formed a huge structure like a pair of scales, one of which (the water-pump) was loaded with weights so as to be slightly heavier than the other (the steam engine).
NEWCOMEN’S ENGINE
To work it, steam was generated in the boiler at a pressure slightly greater than atmospheric. By the opening of a cock steam was admitted to the cylinder, below the piston, which was initially117 at rest in its highest position. The steam having filled the cylinder and expelled nearly all the air, the cock was shut and the cylinder was chilled by an external spray of cold water. Whereupon, as soon as the steam in the cylinder began to condense, the piston, forced down by the now unbalanced atmospheric pressure above it, began to descend118. As soon as it had completed its downward stroke steam was again admitted beneath the piston, and, the pressure on the two sides of the piston becoming equal, the piston began to move up again to its original position. And so on.
This was the original Newcomen engine. Even in this primitive form it far surpassed Savery’s in economy of fuel and in safety. It had, too, far greater flexibility119 in the manner105 in which its power could be applied; it could be used not only to lift a certain volume of water through a relatively120 small height, but a smaller volume through a greater height: which was a desideratum in the case of deep mines like those of Cornwall. In 1720 an engine was erected at Wheal Fortune mine having a cylinder nearly four feet in diameter and drawing water, at fifteen strokes a minute, from a depth of 180 feet.
Yet it was apparent that the engine was in many respects inefficient121. The cocks, for instance, which controlled the motion of the piston had to be opened and shut by a man. Sometimes he let the piston rise too far, in fact, right out of the cylinder; sometimes he let it down too fast, so as to damage the engine. Again, the external spraying of the cylinder at every stroke to induce condensation of the steam within was an obviously clumsy and primitive operation. It was not long before external spraying gave place to internal cooling of the steam by the injection of water; this method being discovered, it is said, as the result of a leaky piston allowing its sealing water to pass, yet giving unaccountably good results. The difficulties with the cocks were overcome by the laziness or initiative of a youth named Humphrey Potter, who attached some strings122 and catches to the cocks of an engine which he was employed to work at Wolverhampton.77
With these improvements the engine remained practically without alteration123 for the next forty years. Its greatest sphere of usefulness was in the northern coalfields, where cheap and abundant fuel was close at hand. In Cornwall, until by special legislation the duty on seaborne coal was remitted124 when used for Newcomen’s engine, the cost of fuel proved a great obstacle to its use.
§
In 1764 James Watt, an instrument maker125 employed on work for Glasgow College, was given the task of repairing a working model of a Newcomen engine.
A man of serious and philosophical mind, an intimate friend106 of Professor Robison, the physicist, and acquainted with the famous Dr. Black of Edinburgh, then in the thick of his researches on the phenomena of latent heat, Watt often discussed with these two scientists the possibility of improving the steam engine; which apparatus was still only employed for the purpose of pumping water, and which was so clumsy and so wasteful of fuel as to be comparatively little used. To this end he was induced to try some experiments on the production and condensation of steam. The results of these, and a knowledge of the newly discovered phenomenon of latent heat,78 convinced him that the existing cycle of operations in the engine was fundamentally inefficient, and that improvement was to be sought in the engine itself rather than in the boiler, which was the element which was receiving most attention from contemporary investigators.
In particular, he clearly discerned the thermal126 inefficiency127 of the Newcomen engine: the waste of heat involved in alternately heating and cooling the large metal cylinder, which absorbed such immense quantities of fuel. Watt’s first idea was, to lag the cylinder in wood so as to prevent all outward radiation. But the result of a trial of a lagged cylinder was disappointing. A gain was certainly obtained in that the steam, when admitted to the cylinder, did not require to raise by partial condensation the temperature of the walls; it exerted its expansive force at once and the piston rose. But on the other hand much greater difficulty was experienced in condensing it when a vacuum was required, for the down stroke. Moreover it was observed that an increase in the amount of injection water only made matters worse.
Watt was faced with a dilemma128, and he overcame it by a series of studies in the properties of steam which constitute, perhaps, the highest achievement of this workman-philosopher.
Out of all his experiments two conclusions were drawn129 by him; first, that the lower the temperature of condensation of steam the more perfect the vacuum thereby formed; second, that the temperature of the cylinder should be as nearly as possible equal to that of the steam admitted to it. In Newcomen’s engine these two conditions were obviously incompatible,107 and the problem was,—how could they be reconciled? Early in 1765, while walking one Sunday afternoon in Glasgow Green the idea flashed upon him of condensing the steam in a separate vessel. The steam was generated in a separate vessel, why not produce the vacuum separately? With a view to trying this effect he placed a hollow air-tight chest beneath the steam cylinder, connected with it by a pipe having a stop-cock in it. This new or lower vessel was immersed in a cistern130 of cold water. Upon trial being made, it was found that by this simple contrivance as perfect a vacuum as desired was produced; the speed of the engine was greatly increased, the expenditure131 of fuel radically132 reduced, the walls of the steam cylinder were maintained at a high and constant temperature, and the whole arrangement promised great success. The new vessel Watt called a Condenser133.
Fresh difficulties now arose. As the engine worked, the condenser gradually filled with the condensed steam and had to be emptied periodically. The water in which it was immersed became so hot, by absorbing the heat of the steam, that it frequently required changing. Watt promptly134 called in aid two new auxiliaries135, two organs whose motion was derived136 from the main beam of the engine: the Air Pump and the Circulating Pump. By these expedients137 the action of the condenser was rendered satisfactory, and an engine resulted which had a fuel-consumption less than half that of Newcomen’s engine.
Much, he saw, yet remained to be done to obtain economical expenditure of steam. In particular the open-topped cylinder, whose walls were chilled at every descent of the piston by contact with atmospheric air, was an obvious source of inefficiency. He therefore determined138 not to expose the walls to the atmosphere at all, but to enclose all the space above the piston; and, thinking thus, he conceived the idea of replacing the air above the piston by steam, an equally powerful agent. The cylinder he proposed to maintain at a constant high temperature by means of a layer of hot steam with which he encased it, which he called a steam jacket. And so the atmospheric engine as left by Newcomen evolved into the single-acting steam engine of Watt;—an engine in which steam was still used below the piston, only to displace air and provide a vacuized space for the downward motion of the piston; but in which steam now acted positively139 above the108 piston, in lieu of atmospheric air, to drive it down. It was still a sufficiently primitive form of prime mover. The piston was still lifted by the counterweight at the other end of the timber cross-beam; the engine had not yet developed the organs necessary for producing a satisfactory rotary140 motion. This step was shortly to follow.
In 1769 Watt obtained his patent for the “double impulse,” as it was called; and by this step, by the transition from a single- to a double-acting engine, the possibilities of such machines for every variety of application first came into general view. This stage of the development showed to the full the ingenuity of Watt’s mechanical mind. By the invention of the slide-valve he distributed steam to the top and to the bottom of the cylinder, and in appropriate phase with these actions opened the two ends to the condenser; so that the piston was actuated positively and by an equal force on both up and down strokes. The chain by which the piston had been suspended was no longer adequate; it was replaced by a rod. A straight-line motion was required for the top end of the rod; so he formed a rack, to gear with the circular end or horse-head of the beam. But this noisy mechanism141 was soon superseded by another contrivance, the beautifully simple “parallel motion,” in which two circular motions are combined to produce one which is rectilinear. This was patented in ’84.
Four years before this, that ancient mechanism the crank and connecting rod had been applied, together with a flywheel, to transform the reciprocating motion of a steam engine into a rotary motion; and the non-possession of this invention of James Pickard’s proved for a time a stumbling-block to Watt in his further development of his engine. Watt would have nothing to do with it. By now he had joined his fortunes with those of Mr. Boulton, of Soho, Birmingham, a man of great business ability, in conjunction with whom he was engaged in constructing engines in large numbers to suit the varying conditions of the mines in Cornwall and the North. Considerable ingenuity was expended142 by him in trying to circumvent143 the troublesome crank of Pickard, and many devices were produced, the most noteworthy being the “sun-and-planet wheels,” which enabled him with some sacrifice of simplicity144 to obtain the rotary motion desired.
Watt seemed to be borne along by the momentum145 of his109 own discoveries; every inquiry yielded him valuable reward. For some time he had studied the possibility of reducing the violence with which the piston, now positively steam-driven on both sides, came to the end of its stroke. This problem led him to the discovery of the advantage of using steam expansively: of cutting off the inflow of steam before the piston had travelled more than a fraction of its stroke, and letting its inherent elastic82 force impel88 it through the remainder of its journey, the steam meanwhile expanding and thus exerting a continuously decreasing force. Later came the throttle146 valve, and the centrifugal governor for controlling the speed of rotating engines; there was no end to his ingenuity. And so complete was his inquiry into the possible sources of improvement of the steam engine, that he even considered means of regulating the force which the piston exerted on the crank throughout its working stroke, a force which was compounded of the steam pressure itself and of the mass-acceleration of the piston and other moving parts.
Another cardinal147 invention followed: the Indicator148. The principle of the indicator is now applied to every form and kind of piston engine. It is a reproduction on a small scale of the essential part of the engine itself; a small piston, held by a spring and moving in a cylinder connected by a pipe with the cylinder of the engine itself, shows by the degree of compression imparted to the spring the gaseous pressure actually present at any moment in the engine cylinder. By recording149 the position of the indicator piston on a paper wrapped round a rotating drum whose motion represents the motion of the engine’s piston, a diagram is obtained which by its area measures the work done by the steam during the stroke of the engine.
This instrument was designed by Watt to give his firm some standard of work which would serve as a basis for the power of each engine, on which to charge their customers; their engines being sold by the horse-power. But its usefulness far exceeded the immediate102 purpose for which it was produced. Its diagram, to the eye of an expert, gave valuable information in respect of the setting of the valves, the tightness of the piston, the dryness of the steam, the degree of vacuum in the condenser, and, generally, of the state of efficiency of the engine. “It would be difficult to exaggerate the part which this little instrument has played in the evolution of the steam engine. The eminently110 philosophic49 notion of an indicator diagram is fundamental in the theory of thermodynamics; the instrument itself is to the steam engineer what the stethoscope is to the physician, and more, for with it he not only diagnoses the ailments150 of a faulty machine, whether in one or another of its organs, but gauges151 its power in health.”79
§
We have now traced the evolution of the steam engine up to the time when it was first adapted to the propulsion of war-vessels. There we must leave it. In a later chapter we shall consider the evolution of the propelling machinery152 in its relation, especially, to the military qualities of ships. A few observations will be sufficient to illustrate153 the conditions, as to design, practice, and material, under which the steam engine made its appearance in the royal navy.
After the death of Watt all improvement of steam machinery was strenuously154 opposed by the combined force of prejudice and vested interest. The great Watt himself had set his face against the use of high-pressure steam, and, such was the lingering force of his authority, years passed before the general public gave assent155 to the advances made by his talented successors—Hornblower, Woolf, Evans, and Trevithick. Before the end of the eighteenth century the first steps had been made to use the force of steam for driving ships. Before Trafalgar was fought steam engines had made their appearance in the royal dockyards. Then there was a pause; and many years passed by before steam propulsion was admitted to be a necessity for certain classes of war-vessels.
An interesting account of the state of design and practice as it existed on ship-board in the year of Queen Victoria’s accession is given by Commander Robert Otway, R.N., in his treatise on Steam Navigation. Low-pressure principles are still in vogue156; steam is generated still, at a pressure not exceeding three pounds per square inch, in rectangular boilers157 of various forms according to the fancy of the maker, scarcely two being alike. The engines are also of varying forms, every size, variety, and power being deemed suitable for similar vessels. They are amazingly ponderous158: weigh about twelve hundredweight, and the boilers eight hundredweight, to the horsepower. The engines of all makers159 exhibit the greatest variations111 in the relative dimensions of their various parts: one firm embodies160 a massive frame and light moving rods and shafts161, another adopts massive rods and shafts, and supports them within the lightest framework. The author advocates a correct design and a “total dispensation of all superfluous162 ornament72.”
CONNECTING ROD
From Otway
Already, however, following the example of the Cornish mines, the builders of steam vessels were at this time beginning to adopt high-pressure steam, generated at a pressure of ten to fifteen pounds per square inch in cylindrical163 boilers, and working expansively—“doing work in the cylinder by its elasticity alone”—before returning to the jet condenser. This improvement, strenuously opposed by orthodox engineers as being unsafe for ship practice, was introduced first into the Packet Establishment at Falmouth, and then, tardily164, into Government steamers. It gave a gain in economy measured by the saving of “thousands of bushels of coal per month.” Steam engines working on the low-pressure system used from nine to twelve pounds of coal per hour, for each horse-power. These engines were carried in vessels “built on the scantling of 10-ton brigs,” of great draught165 and of such small coal capacity—about 35 tons, on an average—that when proceeding166 out of home waters “they were burthened with, at the least, four days’ more fuel, on their decks (top hamper), in addition to that which already filled up their coal-boxes below.” Boilers emitted black clouds of smoke at sea. In harbour the paddle-wheels had to be turned daily, if but a few float-boards only, by the united force of the crew. “Coaling ship” was carried out with the help of convicts from the hulks:—“pampered delinquents,” observes the author, “whose very movements are characteristic of their moral dispositions—being thieves of time; for their whole day’s duty is not worth an hour’s purchase.”
In these unattractive circumstances the steam engine, most wonderful contrivance of the brain and hand of man, presented itself for embodiment in the navy, by the personnel of which it was regarded, not without reason, as an unmitigated evil.
点击
收听单词发音
收听单词发音 |
1
manifestation
|
|
| n.表现形式；表明；现象 | |
参考例句： |
|
|
|
|
2
monk
|
|
| n.和尚，僧侣，修道士 | |
参考例句： |
|
|
|
|
3
gunpowder
|
|
| n.火药 | |
参考例句： |
|
|
|
|
4
ingenuity
|
|
| n.别出心裁；善于发明创造 | |
参考例句： |
|
|
|
|
5
artillery
|
|
| n.(军)火炮，大炮；炮兵(部队) | |
参考例句： |
|
|
|
|
6
logic
|
|
| n.逻辑(学)；逻辑性 | |
参考例句： |
|
|
|
|
7
watt
|
|
| n.瓦，瓦特 | |
参考例句： |
|
|
|
|
8
complexity
|
|
| n.复杂(性)，复杂的事物 | |
参考例句： |
|
|
|
|
9
diffusion
|
|
| n.流布；普及；散漫 | |
参考例句： |
|
|
|
|
10
maturity
|
|
| n.成熟；完成；(支票、债券等)到期 | |
参考例句： |
|
|
|
|
11
wrought
|
|
| v.引起；以…原料制作；运转；adj.制造的 | |
参考例句： |
|
|
|
|
12
civilized
|
|
| a.有教养的，文雅的 | |
参考例句： |
|
|
|
|
13
forth
|
|
| adv.向前；向外，往外 | |
参考例句： |
|
|
|
|
14
altercations
|
|
| n.争辩，争吵( altercation的名词复数 ) | |
参考例句： |
|
|
|
|
15
recital
|
|
| n.朗诵，独奏会，独唱会 | |
参考例句： |
|
|
|
|
16
worthy
|
|
| adj.(of)值得的，配得上的；有价值的 | |
参考例句： |
|
|
|
|
17
investigation
|
|
| n.调查，调查研究 | |
参考例句： |
|
|
|
|
18
drudge
|
|
| n.劳碌的人；v.做苦工，操劳 | |
参考例句： |
|
|
|
|
19
embodied
|
|
| v.表现( embody的过去式和过去分词 )；象征；包括；包含 | |
参考例句： |
|
|
|
|
20
Christian
|
|
| adj.基督教徒的；n.基督教徒 | |
参考例句： |
|
|
|
|
21
treatise
|
|
| n.专著；(专题)论文 | |
参考例句： |
|
|
|
|
22
primitive
|
|
| adj.原始的；简单的；n.原(始)人，原始事物 | |
参考例句： |
|
|
|
|
23
reactionary
|
|
| n.反动者，反动主义者；adj.反动的，反动主义的，反对改革的 | |
参考例句： |
|
|
|
|
24
tangentially
|
|
| adv.无关地 | |
参考例句： |
|
|
|
|
25
periphery
|
|
| n.(圆体的)外面；周围 | |
参考例句： |
|
|
|
|
26
apparatus
|
|
| n.装置，器械；器具，设备 | |
参考例句： |
|
|
|
|
27
spherical
|
|
| adj.球形的；球面的 | |
参考例句： |
|
|
|
|
28
vessel
|
|
| n.船舶；容器，器皿；管，导管，血管 | |
参考例句： |
|
|
|
|
29
motive
|
|
| n.动机，目的；adv.发动的，运动的 | |
参考例句： |
|
|
|
|
30
revival
|
|
| n.复兴，复苏，（精力、活力等的）重振 | |
参考例句： |
|
|
|
|
31
phenomena
|
|
| n.现象 | |
参考例句： |
|
|
|
|
32
sweeping
|
|
| adj.范围广大的，一扫无遗的 | |
参考例句： |
|
|
|
|
33
stifled
|
|
| （使）窒息， （使）窒闷( stifle的过去式和过去分词 )； 镇压，遏制； 堵 | |
参考例句： |
|
|
|
|
34
votaries
|
|
| n.信徒( votary的名词复数 )；追随者；（天主教）修士；修女 | |
参考例句： |
|
|
|
|
|
35
formulate
|
|
| v.用公式表示；规划；设计；系统地阐述 | |
参考例句： |
|
|
|
|
36
equilibrium
|
|
| n.平衡，均衡，相称，均势，平静 | |
参考例句： |
|
|
|
|
37
ascent
|
|
| n.(声望或地位)提高；上升，升高；登高 | |
参考例句： |
|
|
|
|
38
barometer
|
|
| n.气压表，睛雨表，反应指标 | |
参考例句： |
|
|
|
|
39
virtue
|
|
| n.德行，美德；贞操；优点；功效，效力 | |
参考例句： |
|
|
|
|
40
atmospheric
|
|
| adj.大气的，空气的；大气层的；大气所引起的 | |
参考例句： |
|
|
|
|
41
enunciated
|
|
| v.（清晰地）发音( enunciate的过去式和过去分词 )；确切地说明 | |
参考例句： |
|
|
|
|
42
royalty
|
|
| n.皇家，皇族 | |
参考例句： |
|
|
|
|
43
physicist
|
|
| n.物理学家，研究物理学的人 | |
参考例句： |
|
|
|
|
44
eminent
|
|
| adj.显赫的，杰出的，有名的，优良的 | |
参考例句： |
|
|
|
|
45
inquiry
|
|
| n.打听，询问，调查，查问 | |
参考例句： |
|
|
|
|
46
demolish
|
|
| v.拆毁(建筑物等)，推翻(计划、制度等) | |
参考例句： |
|
|
|
|
47
reigning
|
|
| adj.统治的，起支配作用的 | |
参考例句： |
|
|
|
|
48
enrolled
|
|
| adj.入学登记了的v.[亦作enrol]( enroll的过去式和过去分词 )；登记，招收，使入伍（或入会、入学等），参加，成为成员；记入名册；卷起，包起 | |
参考例句： |
|
|
|
|
49
philosophic
|
|
| adj.哲学的，贤明的 | |
参考例句： |
|
|
|
|
50
philosophical
|
|
| adj.哲学家的，哲学上的，达观的 | |
参考例句： |
|
|
|
|
51
inception
|
|
| n.开端，开始，取得学位 | |
参考例句： |
|
|
|
|
52
wren
|
|
| n.鹪鹩；英国皇家海军女子服务队成员 | |
参考例句： |
|
|
|
|
53
majesty
|
|
| n.雄伟，壮丽，庄严，威严；最高权威，王权 | |
参考例句： |
|
|
|
|
54
speculations
|
|
| n.投机买卖( speculation的名词复数 )；思考；投机活动；推断 | |
参考例句： |
|
|
|
|
55
mightily
|
|
| ad.强烈地；非常地 | |
参考例句： |
|
|
|
|
56
noted
|
|
| adj.著名的，知名的 | |
参考例句： |
|
|
|
|
57
distinguished
|
|
| adj.卓越的，杰出的，著名的 | |
参考例句： |
|
|
|
|
58
discourse
|
|
| n.论文，演说；谈话；话语；vi.讲述，著述 | |
参考例句： |
|
|
|
|
59
exhausted
|
|
| adj.极其疲惫的，精疲力尽的 | |
参考例句： |
|
|
|
|
60
upwards
|
|
| adv.向上，在更高处...以上 | |
参考例句： |
|
|
|
|
61
ram
|
|
| (random access memory)随机存取存储器 | |
参考例句： |
|
|
|
|
62
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： |
|
|
|
|
63
cannon
|
|
| n.大炮，火炮；飞机上的机关炮 | |
参考例句： |
|
|
|
|
64
interim
|
|
| adj.暂时的，临时的；n.间歇，过渡期间 | |
参考例句： |
|
|
|
|
65
inexplicable
|
|
| adj.无法解释的，难理解的 | |
参考例句： |
|
|
|
|
66
paradoxes
|
|
| n.似非而是的隽语，看似矛盾而实际却可能正确的说法( paradox的名词复数 )；用于语言文学中的上述隽语；有矛盾特点的人[事物，情况] | |
参考例句： |
|
|
|
|
67
investigators
|
|
| n.调查者，审查者( investigator的名词复数 ) | |
参考例句： |
|
|
|
|
68
sufficiently
|
|
| adv.足够地，充分地 | |
参考例句： |
|
|
|
|
69
substantiated
|
|
| v.用事实支持（某主张、说法等），证明，证实( substantiate的过去式和过去分词 ) | |
参考例句： |
|
|
|
|
70
substantiate
|
|
| v.证实；证明...有根据 | |
参考例句： |
|
|
|
|
71
ornamental
|
|
| adj.装饰的；作装饰用的；n.装饰品；观赏植物 | |
参考例句： |
|
|
|
|
72
ornament
|
|
| v.装饰，美化；n.装饰，装饰物 | |
参考例句： |
|
|
|
|
73
superseded
|
|
| [医]被代替的，废弃的 | |
参考例句： |
|
|
|
|
74
utilitarian
|
|
| adj.实用的，功利的 | |
参考例句： |
|
|
|
|
75
fens
|
|
| n.（尤指英格兰东部的）沼泽地带( fen的名词复数 ) | |
参考例句： |
|
|
|
|
76
gaseous
|
|
| adj.气体的，气态的 | |
参考例句： |
|
|
|
|
77
piston
|
|
| n.活塞 | |
参考例句： |
|
|
|
|
78
applied
|
|
| adj.应用的；v.应用，适用 | |
参考例句： |
|
|
|
|
79
cylinder
|
|
| n.圆筒，柱(面)，汽缸 | |
参考例句： |
|
|
|
|
80
reciprocating
|
|
| adj.往复的；来回的；交替的；摆动的v.报答，酬答( reciprocate的现在分词 )；（机器的部件）直线往复运动 | |
参考例句： |
|
|
|
|
81
elasticity
|
|
| n.弹性，伸缩力 | |
参考例句： |
|
|
|
|
82
elastic
|
|
| n.橡皮圈，松紧带；adj.有弹性的；灵活的 | |
参考例句： |
|
|
|
|
83
memorable
|
|
| adj.值得回忆的，难忘的，特别的，显著的 | |
参考例句： |
|
|
|
|
84
utilizing
|
|
| v.利用，使用( utilize的现在分词 ) | |
参考例句： |
|
|
|
|
85
combustion
|
|
| n.燃烧；氧化；骚动 | |
参考例句： |
|
|
|
|
86
abject
|
|
| adj.极可怜的，卑屈的 | |
参考例句： |
|
|
|
|
87
ERECTED
|
|
| adj. 直立的，竖立的，笔直的 vt. 使 ... 直立，建立 | |
参考例句： |
|
|
|
|
88
impel
|
|
| v.推动；激励，迫使 | |
参考例句： |
|
|
|
|
89
omission
|
|
| n.省略，删节；遗漏或省略的事物，冗长 | |
参考例句： |
|
|
|
|
90
acting
|
|
| n.演戏，行为，假装；adj.代理的，临时的，演出用的 | |
参考例句： |
|
|
|
|
91
thereby
|
|
| adv.因此，从而 | |
参考例句： |
|
|
|
|
92
chambers
|
|
| n.房间( chamber的名词复数 )；（议会的）议院；卧室；会议厅 | |
参考例句： |
|
|
|
|
93
chamber
|
|
| n.房间，寝室；会议厅；议院；会所 | |
参考例句： |
|
|
|
|
94
originality
|
|
| n.创造力，独创性；新颖 | |
参考例句： |
|
|
|
|
95
specify
|
|
| vt.指定，详细说明 | |
参考例句： |
|
|
|
|
96
boiler
|
|
| n.锅炉；煮器(壶，锅等) | |
参考例句： |
|
|
|
|
97
imputed
|
|
| v.把（错误等）归咎于( impute的过去式和过去分词 ) | |
参考例句： |
|
|
|
|
98
conceal
|
|
| v.隐藏，隐瞒，隐蔽 | |
参考例句： |
|
|
|
|
99
flask
|
|
| n.瓶，火药筒，砂箱 | |
参考例句： |
|
|
|
|
100
tavern
|
|
| n.小旅馆，客栈；小酒店 | |
参考例句： |
|
|
|
|
101
plunged
|
|
| v.颠簸( plunge的过去式和过去分词 )；暴跌；骤降；突降 | |
参考例句： |
|
|
|
|
102
immediate
|
|
| adj.立即的；直接的，最接近的；紧靠的 | |
参考例句： |
|
|
|
|
103
condensation
|
|
| n.压缩，浓缩；凝结的水珠 | |
参考例句： |
|
|
|
|
104
bias
|
|
| n.偏见，偏心，偏袒；vt.使有偏见 | |
参考例句： |
|
|
|
|
105
testimony
|
|
| n.证词；见证，证明 | |
参考例句： |
|
|
|
|
106
wasteful
|
|
| adj.（造成）浪费的，挥霍的 | |
参考例句： |
|
|
|
|
107
augmenting
|
|
| 使扩张 | |
参考例句： |
|
|
|
|
108
solder
|
|
| v.焊接，焊在一起；n.焊料，焊锡 | |
参考例句： |
|
|
|
|
109
joints
|
|
| 接头( joint的名词复数 )； 关节； 公共场所（尤指价格低廉的饮食和娱乐场所） （非正式）； 一块烤肉 （英式英语） | |
参考例句： |
|
|
|
|
110
undertaking
|
|
| n.保证，许诺，事业 | |
参考例句： |
|
|
|
|
111
entirely
|
|
| ad.全部地，完整地；完全地，彻底地 | |
参考例句： |
|
|
|
|
112
vertical
|
|
| adj.垂直的，顶点的，纵向的；n.垂直物，垂直的位置 | |
参考例句： |
|
|
|
|
113
brass
|
|
| n.黄铜；黄铜器，铜管乐器 | |
参考例句： |
|
|
|
|
114
standing
|
|
| n.持续，地位；adj.永久的，不动的，直立的，不流动的 | |
参考例句： |
|
|
|
|
115
axis
|
|
| n.轴，轴线，中心线；坐标轴，基准线 | |
参考例句： |
|
|
|
|
116
vertically
|
|
| adv.垂直地 | |
参考例句： |
|
|
|
|
117
initially
|
|
| adv.最初，开始 | |
参考例句： |
|
|
|
|
118
descend
|
|
| vt./vi.传下来，下来，下降 | |
参考例句： |
|
|
|
|
119
flexibility
|
|
| n.柔韧性，弹性，（光的）折射性，灵活性 | |
参考例句： |
|
|
|
|
120
relatively
|
|
| adv.比较...地，相对地 | |
参考例句： |
|
|
|
|
121
inefficient
|
|
| adj.效率低的，无效的 | |
参考例句： |
|
|
|
|
122
strings
|
|
| n.弦 | |
参考例句： |
|
|
|
|
123
alteration
|
|
| n.变更，改变；蚀变 | |
参考例句： |
|
|
|
|
124
remitted
|
|
| v.免除（债务），宽恕( remit的过去式和过去分词 )；使某事缓和；寄回，传送 | |
参考例句： |
|
|
|
|
125
maker
|
|
| n.制造者，制造商 | |
参考例句： |
|
|
|
|
126
thermal
|
|
| adj.热的，由热造成的；保暖的 | |
参考例句： |
|
|
|
|
127
inefficiency
|
|
| n.无效率，无能；无效率事例 | |
参考例句： |
|
|
|
|
128
dilemma
|
|
| n.困境，进退两难的局面 | |
参考例句： |
|
|
|
|
129
drawn
|
|
| v.拖，拉，拔出；adj.憔悴的，紧张的 | |
参考例句： |
|
|
|
|
130
cistern
|
|
| n.贮水池 | |
参考例句： |
|
|
|
|
131
expenditure
|
|
| n.(时间、劳力、金钱等)支出；使用，消耗 | |
参考例句： |
|
|
|
|
132
radically
|
|
| ad.根本地，本质地 | |
参考例句： |
|
|
|
|
133
condenser
|
|
| n.冷凝器；电容器 | |
参考例句： |
|
|
|
|
134
promptly
|
|
| adv.及时地，敏捷地 | |
参考例句： |
|
|
|
|
135
auxiliaries
|
|
| n.助动词 ( auxiliary的名词复数 )；辅助工，辅助人员 | |
参考例句： |
|
|
|
|
136
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： |
|
|
|
|
137
expedients
|
|
| n.应急有效的，权宜之计的( expedient的名词复数 ) | |
参考例句： |
|
|
|
|
138
determined
|
|
| adj.坚定的；有决心的 | |
参考例句： |
|
|
|
|
139
positively
|
|
| adv.明确地，断然，坚决地；实在，确实 | |
参考例句： |
|
|
|
|
140
rotary
|
|
| adj.(运动等)旋转的；轮转的；转动的 | |
参考例句： |
|
|
|
|
141
mechanism
|
|
| n.机械装置；机构，结构 | |
参考例句： |
|
|
|
|
142
expended
|
|
| v.花费( expend的过去式和过去分词 )；使用（钱等）做某事；用光；耗尽 | |
参考例句： |
|
|
|
|
143
circumvent
|
|
| vt.环绕，包围；对…用计取胜，智胜 | |
参考例句： |
|
|
|
|
144
simplicity
|
|
| n.简单，简易；朴素；直率，单纯 | |
参考例句： |
|
|
|
|
145
momentum
|
|
| n.动力，冲力，势头；动量 | |
参考例句： |
|
|
|
|
146
throttle
|
|
| n.节流阀，节气阀，喉咙；v.扼喉咙，使窒息，压 | |
参考例句： |
|
|
|
|
147
cardinal
|
|
| n.(天主教的)红衣主教；adj.首要的，基本的 | |
参考例句： |
|
|
|
|
148
indicator
|
|
| n.指标；指示物，指示者；指示器 | |
参考例句： |
|
|
|
|
149
recording
|
|
| n.录音，记录 | |
参考例句： |
|
|
|
|
150
ailments
|
|
| 疾病（尤指慢性病），不适( ailment的名词复数 ) | |
参考例句： |
|
|
|
|
151
gauges
|
|
| n.规格( gauge的名词复数 )；厚度；宽度；标准尺寸v.（用仪器）测量( gauge的第三人称单数 )；估计；计量；划分 | |
参考例句： |
|
|
|
|
152
machinery
|
|
| n.(总称)机械，机器；机构 | |
参考例句： |
|
|
|
|
153
illustrate
|
|
| v.举例说明，阐明；图解，加插图 | |
参考例句： |
|
|
|
|
154
strenuously
|
|
| adv.奋发地，费力地 | |
参考例句： |
|
|
|
|
155
assent
|
|
| v.批准，认可；n.批准，认可 | |
参考例句： |
|
|
|
|
156
Vogue
|
|
| n.时髦，时尚；adj.流行的 | |
参考例句： |
|
|
|
|
157
boilers
|
|
| 锅炉，烧水器，水壶( boiler的名词复数 ) | |
参考例句： |
|
|
|
|
158
ponderous
|
|
| adj.沉重的，笨重的，(文章)冗长的 | |
参考例句： |
|
|
|
|
159
makers
|
|
| n.制造者，制造商（maker的复数形式） | |
参考例句： |
|
|
|
|
160
embodies
|
|
| v.表现( embody的第三人称单数 )；象征；包括；包含 | |
参考例句： |
|
|
|
|
161
shafts
|
|
| n.轴( shaft的名词复数 )；（箭、高尔夫球棒等的）杆；通风井；一阵（疼痛、害怕等） | |
参考例句： |
|
|
|
|
162
superfluous
|
|
| adj.过多的，过剩的，多余的 | |
参考例句： |
|
|
|
|
163
cylindrical
|
|
| adj.圆筒形的 | |
参考例句： |
|
|
|
|
164
tardily
|
|
| adv.缓慢 | |
参考例句： |
|
|
|
|
165
draught
|
|
| n.拉，牵引，拖；一网（饮，吸，阵)；顿服药量，通风；v.起草，设计 | |
参考例句： |
|
|
|
|
166
proceeding
|
|
| n.行动，进行，(pl.)会议录，学报 | |
参考例句： |
|
|
|
| 欢迎访问英文小说网 |