1843. 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



321 



history of tlic Cranston Hill Water-works, formed by a rival company, with 

 whom for a time a ruinous competition existed, and whose works it became 

 necessary to purchase, are given at length. The paper then describes the 

 natural filter for the water, which was taken advantage of, by driving tunnels 

 along the borders of the peninsula round which the Clyde sweeps in the form 

 of a horse-shoe. This spot being composed of sand and gravel would, it was 

 argued, form a filter, whence the water could be pumped up and conveyed 

 across the river into the city. Many plans were designed for thus carrying 

 the water; that which was adopted was suggested by Mr. Watt : he pro- 

 posed the use of cast iron pipes, fitted, where necessary, with revolving ball 

 and socket joints, which he then fust introduced, and of which he sent a 

 wooden model to the company, which model was now presented by them to 

 the Institution of Civil Engineers. These pipes adapted themselves to the 

 form of the bed of the river, and the plan was perfectly successful. 



Mr. Telford's experiments upon stone pipes are mentioned, and some re- 

 sults are given. A stone from Rutherglen White quarry, 1 ft. 9 in. long, 

 18 i in. square, with a bore in it 9\ in. diameter, when subjected to a pressure 

 of a column of water from GO to 80 ft. in height, split in the direction of the 

 natural bed. Another stone from the same quarry, 5ft. 2 in. long, 13 in. 

 square, with a bore of 4-j in. diameter in it, did not emit any water until the 

 pressure amounted to 100 ft. head ; after that it discharged water freely, and 

 split when the column a little exceeded 300 feet. A Portland stone, 4 ft. G in. 

 long, 12 in. diameter, with a bore of G in. diameter in it, did not emit any 

 water, nor was there any symptom of fracture under a pressure of 350 feet. 

 Other stone pipes were also experimented upon with such various results, 

 that Mr. Telford arrived at the conclusion, that they could not he relied 

 upon, and accordingly recommended iron pipes. 



The paper is illustrated by a large map of the city of Glasgow, upon which 

 is shown, by different tints, the houses which existed when the water- works 

 were commenced, the ranges of distribution, and the extent of the district 

 for which the company is bound by Act of Parliament to supply water for 

 certain periods during each day. 



Remarks. — Mr. Simpson said that he was well acquainted with the works 

 which had been described, as he had repeatedly visited them professionally ; 

 there were many points of interest attached to them, and the engineering 

 operations were of considerable magnitude and importance. The late Mr. 

 Watt suggested the idea of using the sandy peninsula on the opposite side of 

 the river Clyde to the present works of the Glasgow company at Dalmarnock, 

 as a natural filter, and it succeeded admirably, until the immoderate quantity 

 of water was delivered to the city during the competition with the Cranston 

 Hill Water Company. Of this spot, and the tunnels and wells in it, he pre- 

 sented a tracing. When he was at the works in the year 1833, Mr. Alex- 

 ander Anderson, the then resident engineer, had been pumping water on to 

 the peninsula for many months, and the deficiency of the natural filters, 

 (nearly half the supply at the time) was made up by that means; at first the 

 pumps were worked by rocking shafts connected to the engines across the 

 river; afterwards pumps were erected close to the engines, and the water 

 conveyed across the river through pipes. A very large portion of the supply 

 to the inhabitants was drawn from the mains, without the intervention of 

 cisterns, and a great deal of the water was thus wasted. The filter recom- 

 mended by Mr. Telford was composed of a series of cells tilled with sand, 

 the water passing through them in succession ; this filter was not effective 

 during floods or when the water of the Clyde held in suspension the colour- 

 ing matter from the peat-mosses ; after passing through the first cell little 

 more was accomplished, and the water continued discoloured. 



Mr. Simpson had, however, seen the Clyde water filtered until it was per- 

 fectly bright, by conducting the process very slowly, the rate of motion not 

 exceeding half an inch per hour through the medium — precipitation on the 

 sand evidently took place; he had in some instances accelerated the precipi- 

 tation by previous admixture of alumina or pipeclay and other materials, and 

 had succeeded in throwing down the colouring matter, so that the filters 

 produced perfectly pellucid water. In a filtering bed, properly arranged, the 

 impurities were arrested at and near the planes of ingress — great extents of 

 medium effected little in addition. In some filters which had been worked 

 for nearly sixteen years, it had not been found necessary during that period 

 to change the entire mass of materials. The natural filters of the Glasgow 

 compauy had been injuriously affected by depressing the water in the wells, 

 thereby increasing the pressure of the water on the bed and the foreshores 

 of the river, and thus bringing the particles of the medium into too close 

 contact and forcing obstructions between them. The Glasgow Water-works 

 was an example of the employment of the largest steam-eugiuc power for 

 water-works purposes in Britain ; he believed that at one period the engines 

 at the works were equal to nearly 700 h.p. During the erection, in 1 829, 

 of the second pair of engines, with cylinders of 54 inches diameter, many 

 difficulties were encountered ; in the Vale of the Clyde, large quantities of 

 mud almost in a fluid state lie intermixed with the strata. In sinking the 

 wells for these engines, the mud was met with much nearer the surface than 

 was anticipated, and when tapped, it rose up like a fountain in the bottom of 

 the well ; the pumps were, in consequence, fixed at a higher level than was 

 originally designed. Mr. Crichton, of Sobo, was of opinion that the altera- 

 tion of 4 ft. 5 in. in the level of the pumps was immaterial ; he probably did 

 not calculate upon the water sinking in the filter-wells when the increased 

 pumping power was applied. 



Mr. John Gibb, of Aberdeen, who was consulted about the foundation, 

 bored to 30 feet lower than the bottom of the new well, and found that the 



ground became weaker as the depth increased, so that any attempt to sink 

 the well to the depth required would be very hazardous,. He therefore ad- 

 vised the enlargement of the surface of tin: building under the whole super- 

 structure, with due provision for the weights and strains in the arrangements; 

 that a strong platform should be constructed of Memel logs and planking for 

 the foundation, and the spaces between flic timber to be filled in with ma- 

 sonry flushed in and grouted; this plan was adopted, and proved successful 

 as a foundation, but the depth was insufficient, and the working barrels of 

 the pumps were obliged to be fixed so much above the level of the filters, 

 that they ceased to fill when the water in the tunnels was depressed 22 feet 

 below tlie tops of the pumps. This was a serious disappointment to the 

 company, for whenever the water in the river was low, a corresponding de- 

 pression" occurred in the wells of the filters; and in general, for many hours 

 daily, these two engines only raised as much water as one would have 

 pumped, if the working barrels had been fixed at the proper level. The 

 suction-pipes were inclined towards the filter wells, and the pumps were (lis- 

 taut from them about 110 yards; this, Mr. Simpson considered, was com- 

 paratively of little importance, as he had worked pumps with horizontal suc- 

 tion pipes 500 yards in length. 



Mr. Hawkins recommended slow filtering, without pressure ; some years 

 since he had been engaged in refining sugar by Howard's process, by which 

 the syrup was applied to the filter under a column of 20 feet in height ; out 

 of a certain quantity, 300 gallons were returned unliltered, and by the time 

 GO gallons had been clarified, the filter was choked. He reduced the column 

 to 2 feet, and out of the same quantity G gallons alone were returned, while 

 300 gallons were clearly filtered; this, and numerous other cases, had con- 

 vinced him that pressure was injurious to filtration. 



Mr. Braitbwaite believed, that although slow filtration was generally pre- 

 ferable, yet that the velocity must depend upon the quality as well as the 

 quantity' of matter held in suspension ; this consideration would also regulate 

 the time during which the filter could he worked without cleansing. 



Mr. Hawkins found practically, that half an inch in depth was the utmost 

 that was required to be removed from the surface of the filtering medium 

 when it was cleaned and renewed. 



Mr. Simpson said, that in order to filter properly, there should be exten- 

 sive reservoirs where all the grosser particles could subside or be arrested 

 previously to arriving at the filtering medium ; with due attention to this 

 point he had seen filteriug-beds worked for G7 days consecutively without 

 requiring to be cleansed. 



Ari'ENDIX TO THE LAST PAPER. 



" Description of a cast iron Reservoir erected at Garnet Hill, by the 

 Glasgow Water-works Company." By D. Mackain, M.Iust. C.E. 



A considerable extension of the city of Glasgow is now taking place to the 

 north-west of the old town upon an elevation of upwards of 100 feet above 

 the river; the water-works, which are situated to the east of the city, are 

 already upwards of 4 miles distant from the extreme point of delivery, which 

 is almost daily becoming more remote, and the cost of the supply of water 

 is consequently increased. These circumstances rendered necessary the esta- 

 blishment of a new reservoir, which should be sufficiently high and capacious 

 to command and to supply the district. The ground which was obtained for 

 this purpose was on the declivity of Garnet Hill, and had a fall of 20 feet 

 in 90 feet extent. It was necessary to keep the bottom up as high as pos- 

 sible and yet not to contract the space by thick walls, and to erect Biich a 

 building as should not be offensive to the neighbourhood ; these considera- 

 tions induced the author to recommend the use of iron plates for the reser- 

 voir, which should be masked by a screen of masonry designed by Mr. James 

 Smith, architect of Glasgow. 



The construction is thus described. A bearing wall of 4 ft. Gin. in thick- 

 ness was carried up from the foundation all round to within 1 foot of the 

 floor of the reservoir. A division wall was built across the centre to carry 

 the partition for dividing the reservoir into two parts. The space within 

 these walls was filled in with broken stones, over which was a layer of clay, 

 and then a layer of sand, upon which was placed a flooring of Arbroath pave- 

 ment well jointed with cement, and resting at the sides upon the flanches of 

 the sole plates, which were bedded in a mixture of lime and Roman cement, 

 in such proportions as afforded ample time for the adjustment to be com- 

 pleted. The lower tier of plates was 1 inch, and the upper tier 4^ inch in 

 thickness. Their flandi joints were made secure by inserting between the 

 faces a lead pipe J inch diameter, filled with lint-gasket soaked in red lead 

 and tallow, in addition to which the whole was caulked with a composition 

 of hot lime and linseed oil, which in a short time became very hard. The 

 reservoir is 123 ft. long by 85 ft. 6 in. wide, and 13 ft. 2 in. in depth; it is 

 entirely covered by a malleable irou roof supported upon cast iron pillars. 



The paper is illustrated by two drawings and four lithographs, giving the 

 dimensions of every part of the work, and by a specification of the mode of 

 execution. 



Remarks. — Mr. Simpson said that he had examined the reservoir very 

 carefully, and could bear testimony of the excellent manner in which the 

 work was done. The mode of construction was novel, and had succeeded 

 perfectly, as no leakage had occurred since its election, nor had any incon- 

 venience arisen from the variations of temperature, or from the unequal 



