326 Description of an Invention 



carriage must be brought into the position shown in fig. 1 ; 

 and this can readily be done by stops, whioh are provided 

 in the proper places on the curved bars, tor preventing the 

 wheels from rolling too far; as much water must then be 

 poured into the lock C, as will fill it exactly to the black 

 line d, d, withinside the same ; and if the table on which 

 the model stands be not level, small wedges or chips must 

 be put under the model where necessary, until the surface 

 of the water exactly corresponds, all round the lock, with 

 the top water-mark or line above menlioned : it must like- 

 wise be observed, to place the model across the table, so that 

 the weight h, when hung over the pulley f or g, may be at 

 liberty to descend. Then hang the two-pound weight //, 

 fig. 1, by the line over the pulley j\ at the upper end of the 

 lock ; and the carriage, or load B, A, will be drawn forwards 

 into the position shown at fig. 2, and the water in the 

 lock C will pass through the shuttle to buoy up the cais- 

 son D, and its surface in the lock will descend to the lower 

 level. Again, by shifting the weight to the lower end g, 

 the load will again be brought back, the caisson depressed, 

 and the water forced through the shuttle, again raised to the 

 higher level d, d, in the lock, as in fig. ] . 



Hence it is evident that the water in the lock, with or 

 without a boat therein, may be raised or lowered, by the 

 application of any force to move the carriage or load, hori- 

 zontally on wheels. That when it is intended to pass a boat 

 from the upper to the lower canal, the water in the lock is 

 raised to the top water-level d, d ; the upper gates k, k, are 

 then readily opened, and the boat floated into the lock ; 

 this done, and these gates shut, the water and boat, by 

 withdrawing the load from the caisson, is lowered to the 

 lower level of the canal. The lower gates i, i, are then 

 opened, and the boat floated from the lock to the lower 

 canal. In this operation of lowering a boat, it is evident, 

 that so far from there being a waste of water, a weight of 

 water equal to the boat and its load is raised from the lower 

 to the upper canal ; for when the boat at the upper level first 

 enters the lock, its own weight of water is displaced, and 

 3 forced 



