1886.] on New Applications of the Mechanical Properties of Cork. 447 



ram, you see the regularity of tlie jet has disappeared, it now 

 goes in leaps and bounds. This demonstrates that the elasticity of 

 cork is competent to regulate the flow of water. When air is 

 used for this purpose, the air-vessel has to be filled, and, with 

 most kinds of water, the supply has to be kept up while the ram 

 is working, because water under jDressure absorbs air. For this 

 purpose a " sniff-valve," G, is a necessary part of all rams. It is 

 a minute valve opening inwards, placed just below the inner 

 valve ; at each recoil, a small bubble of air is drawn in and 

 passed into the air-vessel. This "sniff-valve" is a fruitful source 

 of trouble. Its minuteness renders it liable to get stopped up by 

 dirt ; it must not, of course, be submerged, and, if too large, it 

 seriously affects the duty performed by the ram. The use of cork 

 gets rid of all these difficulties, no sniff- valve is needed, the ram will 

 work deeply submerged, and there is no fear of the cork vessel ever 

 getting empty. The duty which even the little ram before you has 

 done is 65 per cent., and larger ones have reached 80 per cent. 



The second novel application of cork is, for the purpose of storing 

 a portion of the energy of the recoil of cannon, for the purpose of 

 expending it afterwards in running them out. 



The result of the explosion of gunpowder in a gun is to drive the 

 shot out in one direction, and to cause the gun to recoil with equal 

 energy the opposite way. To restrain the motion of the gun, " com- 

 pressors" of various kinds are used, and in this country, for modern 

 guns, they are generally hydraulic, that is to say, the force of recoil 

 is expended in causing the gun to mount an inclined plane, and, at 

 the same time, in driving a j)iston into a cylinder full of water, the 

 latter being allowed to squeeze past the piston through apertures, 

 the areas of which are either fixed, or capable of being automatically 

 varied as the gun recedes ; or else the water is driven out of the 

 cylinder through loaded valves. As a rule, the gun is moved out 

 again into its firi^ position by its weight, causing it to run down 

 the inclined plane, up which it had previously recoiled. For naval 

 purposes, however, this plan is inconvenient, because the gun will 

 not run out to windward if the vessel is heeling over, on account of 

 the inclined plane becoming more horizontal, or even inclined in 

 the reverse direction, and should the ship take a permanent list, 

 from a compartment getting full of water, the inconvenience might 

 be very considerable. 



In land service guns, when mounted in barbette, the rising of the 

 gun exposes it and the loading detachment more to the enemy's fire, 

 and in both cases, when placed in ports or embrasures, the ports must 

 be higher than if the gun recoiled horizontally, and will therefore 

 offer a better mark to the enemy's fire, especially that of machine 

 guns, while the sudden rise of the gun in recoiling imposes a severe 

 downward pressure on the deck or on the platform. 



To obviate these disadvantages I have contrived the gun-carriage, a 

 model of which is before you on the table, and a diagram of which, Fig. 5, 



Vol. XI. (No. 80.) 2 g 



