portionate addition to the supply, which induced the magistrates in 1787, to adopt a main of iron pipes, five inches in diameter. Though this measure had the effects of augmenting the quantity of water; nevertheless, the introduction of various improvements, and the erection of buildings, &c., rendered it necessary to have recourse to some other springs, at a greater distance from the city. In 1790, an additional main of iron pipes, seven inches in diameter, was therefore laid down, to convey water from Green Craig to the Castle Hill, at an expense of 20,000l.; and this source furnished about 80,640 cubic feet in the course of every twenty-four hours.

Notwithstanding the successive efforts to augment the supply of water, so as to render it fully commensurate to the various wants and uses of the residents of Edinburgh, and the improved state of the city, still its deficiency gave rise to numerous complaints. The establishments for effecting this important object, being the property of the corporation, the dictates of duty, as well as motives of interest, concurred to urge the adoption of means for obviating the alleged inconveniences. Hence, in 1810, the subject engaged their particular attention; and, in the first instance, the devising of an effective remedy was confided to a committee, composed of the most opulent, enlightened, and influential inhabitants. Afterwards, another committee was formed to afford their assistance, and the persons selected on this occasion, were either Professors in the University of Edinburgh, or engineers, among whom may be enumerated Dr. Hope, Professor Playfair, Messrs. Telford, Rennie, and Jardine;-the researches of the latter being chiefly directed to discover sources from which it would be practicable to obtain an abundant supply of good water. As the latter was a paramount consideration, Dr. Hope analyzed the different waters

which Mr. Jardine pointed out in the environs of Edinburgh; and the results of his scientific examinations were detailed in a report to the committee, who likewise, in 1813, received another report from Mr. Telford, containing a plan and description of the different works that would be necessary for the most ample supply to the metropolis of Scotland.

The mass of useful and satisfactory information afforded by the different documents, occasioned their publication, which excited a high degree of interest. A number of persons soon united to accomplish an object so important; and the principal promoters of the plan consisted of the magistrates, as well as many of the most wealthy and intellectual inhabitants of Edinburgh. In 1819, the subscribers, who had associated for carrying the scheme into effect, were incorporated by an Act of Parliament, authorizing them to raise a capital of 135,0001. in shares of 251. each; and also to assign 1200 of them to the corporation, as a compensation for their interest in the then existing establishments, for supplying water to the habitations in the city and its suburbs.

The source, whence it was determined to procure the water, had its rise on the south side of the Pentland Hills, at the distance of about seven miles from Edinburgh, and denominated Crawley springs; but though these produced great abundance, the quantity was considerably augmented, by collecting it from some others on the north side of the Pentlands, by means of lateral conduits, which extend for about half a mile higher in the valley than the site of the former. As the ground of the valley consisted of a bed of gravel, forty feet deep, it proved peculiarly advantageous, by forming a natural filter for the water, which percolated through the mass before it arrived at the spring-head, which is about 560

feet above the level of the sea, and 360 feet higher than the highest street in Edinburgh.

At Crawley springs is the Fountain-Head House, which has a length of sixty feet, by a breadth of thirty, being covered with an arched roof, and surrounded by a wall. This building contains a cistern forty-five feet long, fifteen wide, and six deep, the whole constructed with free stone. The different reservoirs for supplying Edinburgh, are not only capacious, but very conveniently situate for effecting their objects. One of them is on Heriot's Green, having a circular form, and containing a basin thirty feet diameter, with a depth of ten feet. It is about 270 feet below the Fountain Head;-its purpos being the supply of the southern part of the city. Another reservoir, constructed on the Castle Hill, has a length of forty-three feet, by a width of twenty-eight feet, with a depth of seven feet six inches: the site of this is about 230 feet below the Fountain Head, consequently its altitude is forty feet above the other, and it supplies the northern district of Edinburgh. The average elevation of the streets supplied from the reservoir at Heriot's Green, is about 237 feet above the level of the sea; and the distance of the reservoirs from the Fountain Head is about nine miles; but the supply of Leith, from the same source, being contemplated, pipes have been laid down for carrying it into effect.

With a view to obviate any inconvenience that might result from the flood waters to the mills on the river Esk, a very capacious reservoir has been constructed in the valley of Glencorn. The height of its embankment is about twenty-four yards, and the breadth at the base above 150, its distance from the springs being about one mile. As the expense of constructing this and all the other works far exceeded the sum authorized to be

L

raised by the Act obtained in 1819, the Company procured another Act in 1826, to empower them to augment their capital to 253,0007.

The water is conveyed from its source by a train of strong iron pipes, which vary in their capacity, diminishing as they approach Edinburgh, from twenty to fifteen inches diameter. At the Fountain Head, those of twenty inches commence the series, and continue for a considerable space, when pipes of eighteen inches diameter are introduced to the end of the first 18,300 feet; of which the descent is about sixty-five feet. For the remaining part of the main, pipes of fifteen inches are employed, and the fall of this space is 286 feet, in the length of 27,900 feet. In some parts they have an undulating course, and ascend and descend twenty or thirty feet. The main passes through two tunnels,one of them excavated in the solid rock of the Castle Hill, for a length of 1740 feet, and 120 feet below the reservoir;-the other being conducted under Heriot's Green, seventy or eighty feet below its surface, and having a length of 2160 feet. The reservoir on the Castle Hill communicates with that on Heriot's Green, and large pipes branch off from both, for the plentiful supply of the city, in every direction. The altitude of the source being about 360 feet above the level of Edinburgh, in order to prevent any interruption from occurring in the flow of the water, by the air collecting in the pipes through so great a length, a number of cylindrical vessels, four feet high and eighteen inches wide, have been placed above the pipes, at convenient distances, where, by means of a cock or valve, the air can be discharged without any escape of the water. The strength of the pipes is adapted to sustain a pressure equal to a column of water 800 feet high.