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HISTORY OF ENGINEERING.

Book I.

the foundations are afterwards 42 feet above the valley. The culverts here are 90 feet inlength and 25 feet in diameter, and are double.

At Nodines Run, the aqueduct passes at a considerable elevation by a tunnel in thesolid rock, 810 feet in length; the line then crosses the valley of Tibbetts Brook, wherethe culvert is 107 feet in length, and 6 feet in diameter.

At Ilarlem River, where the aqueduct is to cross, there is a depth of water of 26 feet atordinary high tides, and its width is about 610 feet; here it is intended to build a bridge1420 feet in length, 18 feet in width, between the parapet walls, and 27 feet from out toout. There are to be sixteen piers of stone, six of which will be in the river, and ten onland. The river piers are to be 40 feet by 20 feet, and to have a height of 84 feet, to thespringing of the arches diminishing as they rise. The arches are to span 80 feet, whilstthose on land will span only 50 feet. In the centre the arches are projected to be100 feet above the level of high water ; the height to the top of the parapet walls willconsequently be 116 feet, and the total height about 138 feet; when finished, it is intendedto carry the water over in iron mains, 2 or 3 feet in diameter.

At the Manhattan Valley iron pipes or inverted siphons are to be used, as the valley isupwards of 100 feet below the grade line of the aqueduct.

Twenty-six miles of the works were completed in April, 1840. Ventilators are to beplaced at every mile distant, and the water on its arrival at New York is to be receivedinto a reservoir 35 acres in area, the northern half of which is to have a depth of20 feet, and the southern portion 25 feet; and it was estimated that the quantity of waterwould be about 160,000,000 gallons. Pipes or mains, 30 inches in diameter, are then toconvey the water to another reservoir on Murray Hill, of five acres, and capable of con-taining 20,000,000 gallons, the difference of level of which and that of the pool at Crotonbeing 46 feet, which allows a fall of about 14 inches per mile.

According to the engineer’s report, the whole work, with the exception of the bridgeover Harlem Strait, would be completed in 1842 ; it was proposed, after the cofferdamswere constructed, to lay down pipes which would supply the water, whilst this, the mostdifficult part of the operation was in hand.

Various impediments have occurred during the progress of this gigantic undertaking,which have prolonged it beyond the time specified; it is, however, nearly terminated: itscost is estimated at two millions sterling.

Railroads _The internal improvements that have taken place in America during the

last thirty years, particularly in the extension of railroads, is truly astonishing ; the statesof the Union have endeavoured to rival each other in contributing lines to form one greatnational means of communication ; it seems intended that railroads should spread through-out the whole of this vast continent like the meshes of a net, and embrace every spotoccupied by its inhabitants. The progress already made is sufficient to indicate what willbe done in a few years: when the great works now’ in hand are completed, commerce willderive such increased advantages, that we may hope, not only that the bond of union be-tween the states will be thoroughly cemented, but that the whole people w’ill be broughtmore closely together, and become as it were one family with a common interest.

The railroads, first projected for the purpose of connecting certain towms and districts,w’ere designed without regard to any general plan ; the lines being undertaken by com-panies independent of each other, various and often conflicting regulations were adopted ;and much evil has arisen from this w’ant of unanimity in the several operations. Wheneverchartered companies have united and appointed a board of directors to carry out a plansuited to their common interests, the most beneficial results have been produced.

The first great chain of railroad commences at Portsmouth, in New Hampshire , and hasalmost an uninterrupted course to Pensacola, in Florida . Another line from the same placeextends to Boston, Providence, and Stonington, in Connecticut, where it crosses LongIsland Sound to Greenport, and then continues to Brooklyn , near New Aork ; aftercrossing the river Hudson, it proceeds to Jersey, New Brunswick, Trenton, Philadelphia ,Baltimore, Wilmington , and Washington. From thence to Fredericksburg, Richmond,Petersburg, Gaston, in North Carolina, Raleigh, Columbia, Branchville, and Augusta , inGeorgia, then to West Point, Montgomery, and Pensacola, in Florida . Of this extensiveline of communication nearly the whole is complete, and in the year 1840 upwards of 1600miles were travelled over.

From Boston commences another grand chain, which passes Worcester , West Stockbridge,Albany, Schenectady, Utica, Syracuse, Auburn, Rochester , Attica, and Buffalo. Thelength of this line is about 530 miles.

From New York lines are in progress which, when finished, will extend upwards of 500miles.

From Philadelphia is a line to Sunbury, Williamsport , and Erie, on the lake of that name,a distance of 420 miles.

By means of railroads and canals a distance of 400 miles is accomplished, from Philadel-phia to Columbia, Hollidaysburg, Johnstown, and Pittsburg.