Signor E. Bignami Sormani, assisted by Professor Clericetti, have made several most interesting investigations3 and observations upon the density4 of fresh fallen snow in Milan by means of a simple balance and compressing box. The range of weight of the snow was found to vary as much as eleven times the minimum. A cubic yard from one snowstorm, weighing as much as 814 pounds, while an equal bulk from another fall only weighed 71 pounds. The weight consequently of a cubic foot of the densest5 snow is 30.14 pounds, whilst a cubic foot of water weighs 62.5 pounds, or only about double the weight of this dense6 snow, but which was in all probability little different from ice.
For my purposes, however, I will take a mean[62] between these extreme weights, and assume that the weight of a cubic foot of snow is 16.38 pounds, and that a fall of three inches of snow during the night has caused the ejaculation with which I commenced this chapter to proceed from the aforesaid ratepayer.
The ordinary width of an English street may be taken at thirty-six feet, including the footpaths7, so that on every one hundred yards in length of every street of that width 2,700 cubic feet of snow have fallen, the total weight of which amounts to 44,226 pounds, or very nearly 20 tons, which in actual bulk would represent 100 cubic yards. But as the snow would soon become compressed after falling, I assume that this bulk would be diminished by one-half, and that consequently (without reckoning the snow which has fallen upon roofs and into courts, passages, and alleys8, and which has been quickly shovelled10 therefrom to the street by the occupiers) about 40 ordinary cartloads, weighing half a ton each, would have to be removed from this length of street. Assuming that there are 30 miles of street in a town from which the snow must be immediately removed, 21,144 loads must be carted somewhere, at a cost of at least ￡1,500, assuming that each cart could make ten trips a day, and even then it would take 352 carts a whole week to effect it.
[63]
It may be contended that I have taken an extreme case, and that, of course, the snow does not lie for very long upon the ground in the condition in which it fell, and that hourly it is reducing in bulk and weight by being ground up by the traffic, and finding its way in the form of water into the sewers11, but I have simply advanced the few facts which I have stated in order to give some idea of the labour and cost of snow clearing in a city or town, and I think I cannot do better than at once describe how this important work is carried out in the city of Milan, where the organization and arrangements by which it is accomplished12 with marvellous despatch13, and efficiency, could with advantage be copied by the authorities of any of our towns which are occasionally visited by excessive falls of snow.
In Milan the snow carts are emptied into the navigable canals and numerous watercourses by which the city is intersected; and latterly also into the new sewers in the central portion of the city, which are promptly14 flushed whenever it snows. During the winter of 1879-80 the cost of clearing the 1,656,200 square yards total area of squares, streets, and lanes within the city walls, averaged ￡200 per inch depth of snow fallen, and for the 502,800 square yards outside the walls the average cost was ￡62[64] per inch depth, equivalent in each case to about 1.05d. per cubic yard. Ordinarily the clearing of the more frequented streets is completed within eight or ten hours after it has stopped snowing; and of the rest within 24 hours, not reckoning night. The city is parcelled out into small districts, numbering 112 for last winter, of varying extent according to the importance of the work in each. An average rate of pay per inch depth of snow fallen is settled for the whole area of each separate district, according to its extent and the particular conditions affecting the several streets and squares comprised within it. Each district is allotted15 to a contractor16, who usually associates with himself six to ten partners, besides the labourers whom he employs. He has to find carts, horses, and carters; the necessary implements17—spades, shovels18, brooms, scrapers, mattocks, barrows, &c.—are furnished by the city, under suitable stipulations for ensuring proper care in their use. The contracts are made annually19, and the same persons almost always apply for them again year after year. The contractors20 come principally from the trades that are interrupted by winter, viz.:—Paviors, bricklayers and masons, and gravel21 quarrymen. For the direction and supervision22 of the work the whole city is divided into four sections, over each[65] of which is appointed an engineer, with an assistant, who are aided in the general arrangements by the police surveillance. Payment is made only for work effectually done. In each snowstorm the depth of snow falling, which is the basis of pay, is ascertained23 by means of a number of stone posts, fixed24 in suitable open spaces, clear of shelter from buildings, and each capped with a flat horizontal slab25 of stone. As soon as it stops snowing, or two or three times during a storm of several hours, the depth of snow caught on the slabs26 is measured by the engineer in the presence of two of the contractors in his section. The number of men ordinarily engaged in snow clearing on a winter's day is not less than two thousand, and has sometimes risen to three thousand. The stock of implements found by the city, representing a capital of about ￡1,600, is housed in two stores in opposite quarters of the city. In the winter of 1874-75 the total fall of snow amounted to 40? inches, and the whole expenditure27 for clearing it within the city walls exceeded ￡8,400; while in 1877-78 the fall was only 5? inches, involving an expenditure of less than ￡1,040 for a slightly larger area.
The small cost at which this work is carried out in Milan is accounted for by the low rate of wages and cart hire, and the perfect organization of the system.
[66]
When a fall of snow occurs in Paris, attention is first directed to clearing the footpaths and crossings, so as to ensure uninterrupted foot passenger traffic. The town scavengers sand the roads whenever it is necessary for the carriage traffic, at the same time numerous auxiliaries28 are organised to remove the snow from the principal thoroughfares in the order of their relative importance. To assist in removing the snow the General Omnibus Company are bound by their concession29 to furnish 50 waggons30, and carts are specially31 arranged for with the providers of sand and gravel at the beginning of winter, the contractors for maintaining the public roads being also bound to hold their carts at the disposition32 of the sectional engineers. In certain cases the half-melted snow is swept into the sewers, especially into those carrying warm water. Melting by steam has been tried, when a continuous jet was turned on to a mass of banked snow, but it melted very slowly at first, and the melting ceased after the cavity had increased to a certain size. Two descriptions of snow ploughs are kept in store, one for manual, the other for horse power, but they have never been used, as the coating of snow seldom attains33 sufficient thickness, and it is too quickly compressed and hardened by the traffic. As a rule, the sum allowed in the budget, about[67] ￡7,000, suffices for the extra labour incurred34, but occasionally severe winters cause this to be greatly exceeded, as in 1875-76, when the increase amounted to ￡8,000, and no doubt in the winter that has just passed, 1880-81, the estimate must also have been largely exceeded.
In England one of the greatest difficulties we have to contend against is the disposal of the snow after it has been placed in the cart.
If there is a river close by, it can be taken there and tipped, but this is objectionable if it is a navigable river where dredging has to be done, as it is surprising what a quantity of road scrapings and other matters are always removed with the snow, and these materials naturally sink to the bottom, and add considerably35 to the cost of dredging.
If there are public parks the snow may be heaped in them, provided no damage is done to the grass or paths, as the snow thus heaped takes a considerable time to melt, the first effect of a thaw36 being to consolidate37 it, but a better plan is to deposit it upon any waste spots, if these are not too far from the streets which have to be cleared.
Tipping the snow down the manholes into the sewers has been tried in London and other cities, but has failed through the snow consolidating38, and[68] although lighted gas jets have been turned on to the snow, it has still melted too slowly to be of any practical utility.
It has been suggested that a steam jet should be turned on the snow as it lies in the streets, or after it has been heaped, but I very much doubt the efficacy of this plan, although Messrs. Merryweather & Co., of London, have, I understand, melted a cartload of snow in seven minutes. It might, however, be possible to melt the snow by the heat generated in the furnaces that are destroying the house refuse by fire, and this could be effected without any large expense beyond the cost of cartage of the snow to the dep?ts, which would, of course, be necessary.
Failing an organization such as that of Milan, the following suggestions may be of use to those who have sometimes to grapple with this unproductive work:—
Do not attempt to cart away the snow while it is yet falling, but try to make clear crossings for the foot passengers and to keep the traffic open. If there should be a high wind at the time, and the snow drifts in consequence, cut through the drifts so as to allow the vehicular traffic to continue.
Directly the snow ceases to fall put on all available hands to clear the channel gutters39 and street gratings,[69] in preparation for a sudden thaw, when, if these precautions were not taken, serious flooding and great damage to property might ensue; for the same reason cart away all the snow you can at the bottom of gradients and in the valleys, and also from very narrow streets and passages, &c.
In the wider streets use the snow plough, or with gangs of men (in the snow season there is generally plenty of labour obtainable), shovel9 the snow into a long narrow heap on each side of the street, taking care to leave the channel gutters and gratings quite clear, and a sufficient space between the heaps for at least two lines of traffic. Passages must also be cut at frequent intervals40 through the heaps, in order to allow foot passengers to cross the street, and also to let the water reach the channel gutters as soon as the snow begins to melt.
With regard to the question of clearing the snow from the footpaths irrespective of the larger duty of clearing it from the streets, it is often a disputed point in a town as to whether this should be done by the Urban Authority at the expense of the rates, or by the householders themselves, and this can only be settled where the town has a private improvement act, in which a clause or clauses may be inserted throwing the onus41 of such cleansing42 and sweeping43 of[70] the footpaths upon the several and respective occupiers of houses and buildings. But on whoever the duty rests there is no doubt that the easiest and quickest method of effecting a thorough cleansing of a footpath from snow is by an application of salt, and then to sweep off the slush that is engendered44 with a broom. Medical men and others, however, assert that the practice of putting salt with the snow is to make a freezing mixture, which is detrimental45 to the health of persons walking on such a mixture, and there can be no doubt that excessive cold is caused by this practice, often sufficiently46 severe to crack the flagstones of the foot pavement.
In the City of London the footways are swept once daily by men in the employment of the Commissioners47 of Sewers, and in wet weather those in the main streets are cleansed48 repeatedly during the day, and this has been done, I believe, since the year 1872, although the occupiers are legally liable for the execution of this work.
In Liverpool, also, this is done after a fall of snow, as will appear from the following interesting remarks on the subject, contained in a report by the Superintendent49 of the Scavenging Department in that borough:—
"The only way to compass the removal of snow[71] from the footwalks of the principal thoroughfares within a comparatively short time is by sprinkling them with salt such as is commonly used for agricultural purposes. It is certain that, unaided by the salt, a sufficient number of men cannot be procured50 for the emergency of clearing snow from the footways of the most important thoroughfares. It has been stated by medical authorities that the application of salt to snow is detrimental to the health of people who have to walk through the 'slush' produced by the mixture, and that the excessive cooling of the air surrounding the places where the application has been made is injurious to delicate persons. It, therefore, seems that the application of salt to snow should not be undertaken during the day time, but should be commenced not before 11 p.m., nor continued after 6 a.m., and that only such an area of footwalks should be so treated on any one night as the available staff of men can clear by an early hour the following morning.
"To sweep snow from the footwalks whilst the fall of snow continues, and especially during business hours, appears to be wasteful51 and futile52, and to apply salt during the same periods may be held to be injurious to health.
[72]
"That the snow of an ordinary fall can be removed from the footwalks by an application of salt an hour or so before they are scraped is an ascertained fact, except at least when a moderately severe frost has preceded, accompanied, or followed the snow fall, or when the snow has drifted into extensive accumulations. Were it not for the danger to health by excessive cooling of the air, and for the expense attending the operation, all the impervious53 pavements could be cleared of snow (unless the fall was a heavy one) in a comparatively short time by a liberal application of salt and the employment of the horse sweeping machines as soon as the snow had become sufficiently softened54 to admit of their use."
To these remarks I have nothing to add, except to suggest that in addition to clearing the snow from the footpaths care should also be taken to scrape out and thoroughly55 clear the roof water trunks, which are frequently found crossing the footpavements; if these remain choked damage may ensue to the adjoining property when a thaw commences.
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abominable
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| adj.可厌的，令人憎恶的 | |
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footpath
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| n.小路，人行道 | |
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investigations
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| （正式的）调查( investigation的名词复数 )； 侦查； 科学研究； 学术研究 | |
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density
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| n.密集，密度，浓度 | |
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densest
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| 密集的( dense的最高级 )； 密度大的； 愚笨的； （信息量大得）难理解的 | |
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dense
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| a.密集的，稠密的，浓密的；密度大的 | |
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footpaths
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| 人行小径，人行道( footpath的名词复数 ) | |
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alleys
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| 胡同，小巷( alley的名词复数 )； 小径 | |
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shovel
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| n.铁锨，铲子，一铲之量；v.铲，铲出 | |
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shovelled
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| v.铲子( shovel的过去式和过去分词 )；锹；推土机、挖土机等的)铲；铲形部份 | |
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sewers
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| n.阴沟，污水管，下水道( sewer的名词复数 ) | |
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12
accomplished
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| adj.有才艺的；有造诣的；达到了的 | |
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despatch
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| n./v.(dispatch)派遣；发送；n.急件；新闻报道 | |
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promptly
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| adv.及时地，敏捷地 | |
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allotted
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| 分配，拨给，摊派( allot的过去式和过去分词 ) | |
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contractor
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| n.订约人，承包人，收缩肌 | |
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implements
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| n.工具( implement的名词复数 )；家具；手段；[法律]履行（契约等）v.实现( implement的第三人称单数 )；执行；贯彻；使生效 | |
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shovels
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| n.铲子( shovel的名词复数 )；锹；推土机、挖土机等的)铲；铲形部份v.铲子( shovel的第三人称单数 )；锹；推土机、挖土机等的)铲；铲形部份 | |
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annually
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| adv.一年一次，每年 | |
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contractors
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| n.（建筑、监造中的）承包人( contractor的名词复数 ) | |
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gravel
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| n.砂跞；砂砾层；结石 | |
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supervision
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| n.监督，管理 | |
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ascertained
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| v.弄清，确定，查明( ascertain的过去式和过去分词 ) | |
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fixed
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| adj.固定的，不变的，准备好的；(计算机)固定的 | |
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slab
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| n.平板，厚的切片；v.切成厚板，以平板盖上 | |
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slabs
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| n.厚板，平板，厚片( slab的名词复数 )；厚胶片 | |
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expenditure
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| n.(时间、劳力、金钱等)支出；使用，消耗 | |
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auxiliaries
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| n.助动词 ( auxiliary的名词复数 )；辅助工，辅助人员 | |
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concession
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| n.让步，妥协；特许(权) | |
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waggons
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| 四轮的运货马车( waggon的名词复数 )； 铁路货车； 小手推车 | |
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specially
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| adv.特定地；特殊地；明确地 | |
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disposition
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| n.性情，性格；意向，倾向；排列，部署 | |
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attains
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| （通常经过努力）实现( attain的第三人称单数 )； 达到； 获得； 达到（某年龄、水平、状况） | |
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incurred
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| [医]招致的，遭受的； incur的过去式 | |
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considerably
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| adv.极大地；相当大地；在很大程度上 | |
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thaw
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| v.（使）融化，（使）变得友善；n.融化，缓和 | |
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consolidate
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| v.使加固，使加强；(把...)联为一体，合并 | |
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consolidating
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| v.（使）巩固， （使）加强( consolidate的现在分词 )；（使）合并 | |
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gutters
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| （路边）排水沟( gutter的名词复数 )； 阴沟； （屋顶的）天沟； 贫贱的境地 | |
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intervals
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| 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 | |
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onus
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| n.负担；责任 | |
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cleansing
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| n. 净化(垃圾) adj. 清洁用的 动词cleanse的现在分词 | |
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sweeping
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| adj.范围广大的，一扫无遗的 | |
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44
engendered
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| v.产生（某形势或状况），造成，引起( engender的过去式和过去分词 ) | |
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detrimental
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| adj.损害的，造成伤害的 | |
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46
sufficiently
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| adv.足够地，充分地 | |
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commissioners
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| n.专员( commissioner的名词复数 )；长官；委员；政府部门的长官 | |
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48
cleansed
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| 弄干净，清洗( cleanse的过去式和过去分词 ) | |
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49
superintendent
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| n.监督人，主管，总监；(英国)警务长 | |
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50
procured
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| v.（努力）取得， （设法）获得( procure的过去式和过去分词 )；拉皮条 | |
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51
wasteful
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| adj.（造成）浪费的，挥霍的 | |
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52
futile
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| adj.无效的，无用的，无希望的 | |
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impervious
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| adj.不能渗透的，不能穿过的，不易伤害的 | |
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54
softened
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| （使）变软( soften的过去式和过去分词 )； 缓解打击； 缓和； 安慰 | |
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thoroughly
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| adv.完全地，彻底地，十足地 | |
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