30 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. [28] 



delivering it to the boilers. We have never succeeded in working both 

 at a time, though they work very well singly, and it rarely occurs that 

 we are obliged to use a steam-pump to feed the boilers. 



ASH ELEVATOR AND CHUTE. 



Plate XIX shows a half section of the vessel at the center line of the 

 ash -chute, and Plate XX shows several views and sections of the hoist- 

 ing engine. The object of this machinery is to hoist the ashes and dump 

 them overboard with the least manual labor and to avoid carrying them 

 across the deck. The vertical chute through the ship's bottom has been 

 tried and abandoned, as the ashes soon scoured through the bottom 

 plates of the ship, in the wake of the chute. The steam ejectors, tried in 

 the navy, were abandoned for the reason that the ashes, blown at such 

 a high velocity, very quickly scoured through a 2-inch thick cast-iron 

 pipe; the writer, therefore, designed the diagonal tube (a 10-inch wrought- 

 iron boiler flue) surmounted by a hopper, and the engine referred to. 

 A stream of water (1J inches in diameter) is projected into the hopper 

 while ashes are being dumped, and the velocity of the descending cin- 

 ders, though not great, is sufficient to project them quite clear of the 

 ship's side. The hopper and elbow are of cast iron, and after two years' 

 use they show scarcely any erosion. The principle of the engine is very 

 old, it belonging to that class which is reversed by " changing the ports," 

 i. e., by having an arrangement by which the steam and exhaust ports 

 are changed, the one for the other. For simplicity and fewness of ports 

 the crank-shaft and hoisting drum are one and the same piece of cast 

 iron;, the cylinders are oscillating, their ports being in the trunnions, 

 the motion of the cylinders opening and closing the ports ; the steam- 

 chest between the two cylinders is common to both, and has at its cen- 

 ter a piston valve ; steam enters through the end of the piston valve, 

 and by moving this valve the steam goes to one side of the chest only; 

 by moving the valve in the opposite direction the steam would go to the 

 other side of the valve chest, which latter is divided, by a longitudinal 

 diaphragm, into two compartments ; the exhaust is through one side of 

 the piston valve. By this arrangement it will be seen that when this 

 piston valve is in its middle position no steam can pass into or out of 

 the engine, which of course stops it ; it is also manifest that a move- 

 ment of the valve in one direction will cause the engine to run in one 

 direction, and the opposite motion of the valve will reverse the engine. 

 The piston valve is moved by a lever which has a long slot in it (a, 

 Plate XX) through which the hoisting rope passes ; on the rope there 

 are two stops (knots), so situated that one will press and move the 

 the lever when the bucket is up, and the other when the bucket is down. 

 To operate the machine two men are employed ; the first one fills the 

 bucket and moves the lever, the bucket rises to its stop and is brought 

 to rest ; the second man dumps the bucket into the chute, pulls the 



