CHAPTER II. 

 LOCKS. 



Origin. The date of the invention of locks is somewhat uncertain. By some they 

 are ascribed to the Dutch, and are said to have been originated in 1253; by others 

 they are claimed for Leonardo da Vinci, while still others say that Philip Visconti was 

 the inventor. In the "Annalesdes Ponts et Chaussdes" for 1847 it is stated that the 

 first one was built to facilitate the transport of marble for the Milan cathedral, and 

 Lombardini, an Italian engineer, says this was done by Visconti in 1439 to connect the 

 old and new lakes, the difference of level being about 10 feet, and claims further that 

 da Vinci could not have made use of locks until 1460. 



Description. A lock consists of a rectangular basin called "the chamber," hav- 

 ing side walls of masonry, earth, or timber, connected near the ends by gates of wood 

 or metal. Through the chamber thus formed communication is established between 

 two pools of different level by admitting water from the upper pool through conduits 

 and discharging it into the lower pool at the lower end. 



That part of the lock above the upper gates is called the head bay or fore bay, 

 and is flanked by the head -bay walls, and that below the lower gates the tail bay, flanked 

 by the tail-bay walls. Between the tail-bay walls is the lower coffer-wall, used for 

 coffering the chamber. The gates close at the bottom against sills inclined up stream 

 and called, from their position and construction, the upper and lower miter-sills. The 

 lower miter-sill is generally fastened to a wall connecting the side walls of the lock and 

 called the lower miter-wall, while the upper miter-sill is attached to the lift- or upper 

 miter- wall; this wall also connects the main walls of the lock and is sometimes called 

 the breast-wall. The upper miter-wall frequently contains the filling culverts. The 

 head-bay walls are connected by a cross-wall, sometimes also called the breast-wall, 

 but generally known as the upper coffer-wall. Of the two side walls the inner one is 

 known as the land-wall and the outer as the river-wall. The land-wall generally has 

 wings at its ends extending into the bank. Gate recesses are formed in each wall just 

 above the miter-sills, into which the gates swing when opened, out of the way of pass- 

 ing craft. The recesses are terminated at the lower ends by stones or castings of special 

 construction, known as hollow quoins, into the hollow of which the gate fits when shut. 

 At the up-stream end of the recess is a right angle, round or beveled on its outer face, 

 called a square quoin. 



NOTE. Certain of the illustrations in this and the following chapters are reprinted by permission from "The United 

 States' Public Works' Guide and Register," by Captain W. M. Hlack, Corps of Engineers, U. S. A. 



The first lock ever built on the American continent was erected at the Sou. In the year 1798 a lock 38 feet long, 8 feet 

 wide, with a lift of 9 feet and a draught of 2) feet, was built. It was used by the fur-traders for lifting their he.ivily laden 

 birch-bark canoes to the level of Lake Superior. It was destroyed in 1814 by the United States troops, but the old sills and 

 floor (till remain. The lock was restored some yean ago as a curiosity. 



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