Page:Popular Science Monthly Volume 31.djvu/663

Rh effects of any given change of volume is to measure the ordinates of the curve constructed by actual experiment. As may be supposed, the pressures indicated by experiment are not nearly so regular and steady as corresponding experiments in a gas would be, and the actual form of the curves will depend on the quality of the cork experimented on.

So far as preservation of elasticity during years of compression is concerned, we have the evidence of wine-corks to show that a considerable range of elasticity is retained for a very long time. With respect to cork subjected to repeated compression and extension, there is very little evidence to be offered beyond this, that cork which had been compressed and released in water many thousand times, had not changed its molecular structure in the least, and had continued perfectly serviceable. Cork which has been kept under a pressure of three atmospheres for many weeks, appears to have shrunk to from eighty to eighty-five per cent of its original volume.

Mr. Anderson has brought under notice two novel applications of cork to the arts:

One is in the water-raising apparatus called a hydraulic ram, the structure of which is shown by Fig. 7. The ram consists of an inclined pipe, A, which leads the water from a reservoir into a chamber, B, which terminates in a valve, C, opening inward. Branching up



from the chamber is a passage leading to a valve, D, opening outward and communicating with a regulating-vessel, E, which is usually tilled with air, but which the author prefers to fill with cork and water. Immediately beyond the inner valve is inserted a delivery-pipe, F, which is laid to the spot to which the water has to be pumped, in this case to the fountain-jet in the middle of this pan.

The action of the ram is as follows: The outer valve C, which