282 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[July, 



six-tentlis of nliat falls may be collected. It is easy, therefore, knowing the 

 fall in any given place, and the nature of the surface and subsoil, to calculate 

 what quantity a given extent of surface will produce. 



The calculation must depend very greatly on the substratum of a portion of 

 the ground, but more upon the smoothness and declivity of the surface. If 

 (he surface be smooth and steep, the v\ater runs off so quickly that little sinks 

 into tlie earth. 



The smallest town which Mr. Thorn has applied machinery to is Camp- 

 bcUtown, of 7000 inhabitants, which was supplied at a cost of about 2,500/. 

 AVIien he speaks of a supply, be always means two cubic feet, or about 13 

 gallons per diem for every individual of the population. 



He is awire that that is very much below the consumption in London, 

 but as a family supply merely, I rather think it will be found to exceed that 

 uf London. 



He does not at the moment recollect the returns of consumption that have 

 been made from the water-works in London ; but he has seen them, and 

 heard them explained. Judging from his knowledge of the facts in other 

 towns, he should say that the quantities set down were rarely delivered. 

 Some years ago, he had the means of ascertaining the quantity supplied to 

 Ciasgow, and found that it did not amount to 13 gallons for each, and of 

 which nearlv one-fourth was surt'ered to run waste, from the imperfect state 

 of their works. In Perth, the quantity supplied to each individual was only 

 8 gallons. In Greenock and Paisley, where the pipes are kept constantly 

 full, and there is nothing to prevent the people from using what they please, 

 the quantity taken is less than 12 gallons for each. These facts lead me to 

 (piestion reports which state the family supply beyond 13 gallons per diein. 

 In London, doubtless, the quantity used for watering the streets, for public 

 works and the like, must be very great.— At Campbelltown, a family of live 

 individuals will be supplied with water for about 1$. 4rf. per annum. The 

 tost at Ayr for the same quantitv is 2.v. 2d. ; at Paisley it is 2s. <Jil. In 

 Greenock, I think, it is about 2s. 6rf. Mr. Thorn allows in this case 5 per 

 cent, on the capital employed ; the expense of wear and tear, charge of 

 superintendence, and the like, being always included in his estimate. Ihey 

 are all high pressure services reaching to the tops of the houses ; havmg all 

 the advantages of being enabled to put out tires, and supply the cisterns at 

 ihe tops of houses. He allows besides the 5 per cent, as much as will keep 

 the machinery in complete order. In those towns there is an acclivity, a 

 hill, which gives a high reservoir. He thinks it would in cases where a 

 towu is on a dead Hat be possible profitably to raise the water by mechanical 

 force for application to the several purposes of extinguishing fires, and wash- 

 ing streets and houses, and so on. 



The supply of water for the different towns referred to has been from very 

 difterent distance". The expense has been increased to a very small extent 

 according to the distance. If you go farther from a towu, land is generally 

 cheaper, and there are fewer interruptions to the operations. The cost of 

 making the reservoir is the same, or nearly the same, at whatever distance 

 it be. The increase of expense, therefore, arises from the increased length 

 of the aqueduct only, which is a trifling item in the calculation for the supply 

 of a town. At Greenock, where the aqueduct passes through rugged and 

 impracticable ground, and was a work of no ordinary difficulty, the cost of 

 it was only about 100/. per mile, exclusive of the price of the land, and it is 

 capable of passing a fuU supply for a city of 500,000 inhabitants. 



Mr. Thom stated his practice in laying down water pipes, and in distribut- 

 ing water for the attainment of the object of keeping the water cool, to be as 

 follows :— the situations for the reservoirs, basins, and filters, being obtained, 

 .-IS above described, he proceeds to notice some details of practice which are 

 peculiar, and on which part of the success of his plan is dependent. In 

 making the aqueducts for conveying the water from one reservoir to another, 

 or from the reservoir to the basins, the ordinary practice is to take the most 

 direct line between the extremes ; crossing valleys by aqueduct bridges or 

 embankments, and overcoming the many other difficulties which attend the 

 method by equally expensive expedients. His method is to wind along the 

 slopes, however far it requires to go about, descending only with such a fall 

 as will allow the water to flow with a gentle current. He endeavours to 

 select the course of the aqueduct, so that it may form the main drain of the 

 farms, and be a fence between portions which it is advisable to keep sepa- 

 rated,— possessing, too, the advantage of affording drinking places for the 

 cattle, the aqueduct is, by the farmer, esteemed rather a benefit than other- 

 wise. The detaUs of the formation of the reservoirs, embankments, sluices, 

 and regulating apparatus, cannot be well understood without illustrative 

 figures. The filter he has described; he then noticed some pecidiantics in 

 in his manner of laying the service-pipes from the distribting basins. These 

 pipes are of iron, and, as has been already noticed, are laid so that the water 

 shall always flow along them in one direction, entering at the liigher end and 

 proceeding to the lower end. At the lower end of each range a cleansing 

 cock is fixed, which is opened occasionally to clear out any rust or mud which 

 may have accumulated in the pipe, and which, if allowed to remain, would 

 of course, deteriorate the quality of the water. The pipes are constantly 

 kept full; in addition to the advantages already detailed, as attendant on this, 

 he mentions tlie following :— There is no limit to the quantity that the poorest 

 inhabitant mav take at all times. There is no risk of turbid water being 

 icarried into the houses by the water rushing along empty pipes every time it 

 us set on. 'llic pipes are laid underground to a minimum depth of three feet 

 under the surface uf the iiavemcut; where Ihey can conveniently be laid 

 deeper it is done ; the water is thus kept cooler aud of finer quality, and risk 

 of injury from fro.,t is avoided. In tome cases, in cider to afford private 



houses very fine cold water, he sinks an iron cistern to hold about 20 gallons 

 8 or 10 feet below the bottom of their cellar, and supply it with water by a 

 small lead pipe entering its top. Another small pipe is inserted at about 

 four inches above the bottom of the cistern, and earned up to the cellar 

 where the water is to be drawn off. Thus, for an expense of about 5/., a 

 family is supplied with one of the greatest luxuries which can be enjoyed— 

 pure sparkling ice-cold water. , ■. ■ 



For the altitude necessary to give, for the supply of houses merely, it is 

 enoueh that the water rises to the top of the highest ; but for security against 

 fires, the water should have a pressure sufficient to throw it with great force 

 over the highest house. At Greenock, there is a pressure of 250 feet, which 

 is 150 feet above the surface level of the highest street. 



Supposing there was a dead level, and it was wished to send the water to 

 such a height as to extinguish fire in houses, there should not be less than 

 20 feet head above the house ; less might do, but more is better. 



Mr Thom explained the cause of an accident which occurred at Greenock— 

 " An ill-constructed embankment gave way, and by the torrent of water let 

 loose, 40 lives were lost, and damage done to property to the extent of 6000/. 

 or 7000/. In this embankment the face next the water was very steep, and 

 no care had been taked to made it impervious to water or vermin ; the con- 

 sequence was, that moles and water mice had perforated it like a riddle, 

 during the drought in search of water ; and when the flood came and raised 

 the water above these holes, it rushed through them with such force as to 

 sweep away the embankment to its base in a few minutes." 



Mr Tho'm concluded his evidence by observing—" I may repeat, that I am 

 clearly of opinion that no town ought to be considered fully supphedl with 

 water, unless the pipes are kept constantly full, and arrangements made by 

 which a powerful force of water can be taken from them at a moment s 

 notice, to extinguish fire in any part of the town, high or low. But this, 1 

 fear will be found impracticable without the assistance of Government and 

 the Legislature. So powerful are many of the present water companies, so 

 strong the chain of interest which binds them together, and so large is the 

 capital sunk in the present imperfect works, which the improved system 

 would supersede, that I despair of ever seeing certain towns properly supplied 

 with wholesome water, unless the powerful aid of Government and the Legis- 

 lature are brought to bear down their selfish opposition. And it were clearly 

 better, even to impose a local tax to compensate such companies, than that 

 the health and comfort of the community should continue longer to suffer 

 by withholding from them the first necessary of life— a copious supply of 

 pure water." 



To be contimied. 



ON THE CAU-StB OF TlIK GENERAL FAILURE OF CANALS 

 IN AMERICA." 



By W. R. Casey, Civil Eugiiucr. 

 h is ubviouslhat some inherent defect must exist in American canals gene- 

 rally to have brought about the present deplorable results. It is true that 

 nearly ;ill these works have been constructed by the governments of the dit- 

 ferunt States and Provinces, and under all the well known disadvantages of 

 that system; and. «c might argue «ilh some reason, that in the hands ol 

 private companies they woukl have been more efficiently as wcl as more 

 clu'aply completed, owinR to the superior sagacity, integrity and skill ot the 

 directors and eusjiueers of works carried on l)y private enterprise. Thus it is 

 no uncommon thitiR to see a president, board of directors and engineer at the 

 head of a sm.ill i.rlvale work, costing two or three hundred thousand dollars, 

 in every respect-character, skill and wealth-incomparably above the go- 

 vernment eommisiinners, boards of w orks and their engineers, entrusted with 

 the disposal of mdlions. But admitting all this, it would merely show that 

 the cost of (he works had been too great, while in practice we find, that be- 

 sides this obvious disadvantage, they labour under Ihe still greater one ol 

 having-practically speaking-no income, as in the case of the Chenango 

 canal, which has a gross income of about 13,000 dollars, on a cost of 21 



millions. . ^ . J nu lo 



The only canals «hich now yield a surplus are the Erie and Ohio canals, 

 owned by the States of New York and Ohio, and the Delaware, and Hudson, 

 and Schuylkill canals, owned by private companies in New York and fenn- 

 svlvania.t The Larchine canal in Canada was productive, but bemg now in 

 the hands of a '■ board of works," is not hkely to remain so much longer. 

 Its " enlargement" has been already commenced. Volumes would not convey 

 to the citizens of New York all which that single word conjures up. 



Had the Erie and Ohio canals been left to their own resources their s ock 

 would never have been at par. The former received six milhcns from tolls 

 d.uinsthe first four years of its existence-nearly its entile cost-and the 

 cmptioller shows, doe. 40, p. 45, 1844, that, charging and allowing interest, 

 the balance is 4,179,291 dollars 46 against the canal-omitti ng, of course , 



. This article originally appeared in lUe " American Railroad Journal." 



J The taiial round the falls of the Ohio is of course omitted. 



