Chap. VII.
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CHAP. VH.
ENGINEERING IN THE UNITED STATES OF AMERICA .
United States . Of late years there have been some extensive engineering works practisedthroughout this country which bid fair to rival those of the Old Continent . Admirablyadapted for commerce, its enterprising population are exerting every effort to improve itsharbours, internal navigation, and railroad communication.
The rivers are noble and important, being navigable to a considerable height, intersectingthe country in all directions, and forming deep bays at their mouths. The Hudson for160 miles will admit vessels of 80 tons, and the Susquehannah, the Potowmac, the Dela-ware , are all valuable as the means of internal navigation, as are the Catahouche and theAlabama, which both fall into the Gulf of Mexico .
The Mississippi rises in the latitude of 47° north, and flows south across 18 degrees oflatitude, through a course of 2000 miles. About half way from its source it receives theMissouri, a larger river , which has a course of 2300 miles. Other noble rivers offer everyfacility to trade and commerce ; it has been estimated that the inland navigation amountsto upwards of 23,000 miles, and the basin of this great system of rivers is computed to con-tain 1,099,000 square miles.
Timber, from its abundance, is generally used in the construction of quays, docks, andrailroads throughout America ; and we are indebted to their engineers for some ad-mirable applications of this material to bridges, &c., which are noticed in our account ofcarpentry.
It is not possible to give more than a brief outline of some of their leading works, whicharc increasing rapidly over the whole extent of their vast territory.
The harbours of America are mostly capable of receiving the largest class of vessels, andare all connected by means of inland navigation with the principal towns. In Canada are the harbours of Quebec, Halifax, and Montreal ; and in the United States the chiefare Boston, New York, Philadelphia, Baltimore, Charles Town, and New Orleans , all ofwhich possess great natural advantages, and afford well-sheltered anchorages in deepwater.
Quebec, the capital of Canada, is situated on the St. Lawrence , about 340 miles from itsmouth. The harbour lies between the town and the island of Orleans , and is very com-modious, the water being about 28 fathoms deep, with a tide rising from 17 to 18 feet,and at springs from 23 to 25 feet. It is protected by a citadel built on the headland,called Cape Diamond, 345 feet above the level of the sea ; the fortifications are very strong.In 1812 the first steamboat that plied on the St. Lawrence was launched at Quebec , and nowthe line of steam navigation extends from the Atlantic to Amhurstburg, a distance of morethan 1500 miles. Quebec commands the whole of this internal navigation, which can onlybe carried on between April and November, in consequence of the frozen state of the rivers,large masses of floating ice being kept in constant motion by the tide.
Halifax is the capital of Nova Scotia: the harbour, one of the finest in America , can beentered at all times, being rarely impeded by ice. There is a very extensive dockyard, andthe port is the seat of a considerable fishery. The town is situated on a peninsula on thewest side of Chebucto Bay.
Boston, one of the largest towns in New England, is the capital of Massachusetts : it issituated on a peninsula near the bottom of a large and deep bay ; it is united to the main-land towards the south, by a narrow isthmus called the Neck. Charlestown lies on the northside of the bay, and Dorchester on the south, with both which places Boston communicatesby means of extensive wooden bridges : the bay containing upward of 75 square miles, andstudded with many islands ; it extends along 50 miles of coast, between Cape Ann and CapeCod . The harbour at its mouth is confined between two necks of land, which allow buta narrow passage from the Atlantic .
The quays are simply constructed of earth and timber. A row of piles driven closetogether fonns the face of the quay, secured perpendicularly by walings bolted on to the faceof the quay, and running throughout its whole extent ; diagonal ties are made fast to theinsides of the piles, and large pieces of timber, connected with the facing piles, are laidbehind them, which being embedded as well as the braces by the earth filled in, the wholeis rendered tolerably solid; these diagonal timbers serve the double purpose of struts andties, and operate against any lateral pressure to which the quay may be subjected. Thefilling in with earth is continued to a level of about 5 feet above the ordinary spring tides ;
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