212 On the Modes of Bhipmng Coal. 



and the whole remains fixed ; while the man who accompanies 

 the wacfsron loosens a catch which fastens the bottom of the 

 waggon, and the whole of the coal is at once discharged 

 into the hold of the vessel. 



As soon as the waggon is empty the brake is again 

 slackened, and the counterpoise coming into action brings 

 back the lever and the empty Avaggon into its original 

 position, and the latter is then run off to the line of rail 

 appropriated for the empty waggon. In some instances the 

 levers are nearly 00 feet long, in order that the waggons may 

 be carried far enough out to plum the hatch of a vessel at 

 that distance from the shore, for they are frequently obliged 

 to remain at some distance from the wharf line for want of 

 water in the river to keep them afloat. 



By means of this contrivance from 60 to 80 tons can be 

 put on board a vessel in one hour; and it has this advantage 

 over the spout, that the waggon can always be brought down 

 within a foot or so of the deck of a ship, so that the coal 

 has no greater distance to fall than from the deck to the 

 hold, — and there is, therefore, much less risk of breakage. 



There are several modifications of the principle upon 

 which this drop is made ; the difference consists principally 

 in the arrangements of the counterpoise. In one of these 

 modifications the lever has its centre of motion in the middle 

 of its length, or thereabouts ; while the counterpoise is a 

 fixed weight at the end of the arm. 



3rd. That of vertical drops. This plan coincides with 

 the second, in so far as a counterpoise is used to bring back 

 the empty waggons, — but it differs from it in that there is 

 is no lever ; the waggon is run out upon a platform supported 

 by counterpoises, the motion of which is governed by a 

 break-wheel. The platform and waggon descend together 

 vertically, — one end of the platform working in two cast- 

 iron guides, which are attached to the standards of the fixed 



