348 On the Compressibility of Water. 



md^l^ wHiGh I call a piezometer, and which is represented 

 in Plate XXXII, (PI. 3 of this No.) Fig. 1. The cylinder. A, 

 was three inches diameter, and eighteen inches long. The 

 end, B, was made water tight, by means ofa plate, which was 

 soldered firmly to it. At the other end, C, a cap was made 

 to screw on and off at pleasure ; being also made water-tight. 

 The rod or plungei', D, which was five-sixteenths of an inch 

 in diameter, was made to pass through a tight stuffing box, E. 

 On the rod, immediately above the stuffing box, was fixed a 

 flexible ring, a. A cannon, Fig. 2, of a sufficient size to 

 contain the piezometer, was fixed vertically in the earth, 

 the muzzle being left about eighteen inches above ground, 

 and the touch-hole plugged tight. . At the mouth, a strong 

 cap, A, was firmly screwed on. In the center of this cap, 

 a small forcing pump, B, was tightly screwed, the piston of 

 which was five-eighths of an inch in diameter. There was 

 an aperture, C, in the cap, to introduce a valve, for the pur- 

 pose of ascertaining the degree of pressure. One pound 

 pressure on this valve indicated an atmosphere. The piez- 

 ometer, which was completely filled vsrith water, was intro- 

 duced into the cannon, which was previously filled with 

 water, and additional water forced in until the cap showed 

 signs of leakage; the valve, at the same time, indicating a 

 pressure of one hundred atmospheres. The piezometer was 

 then taken out of the cannon, and the flexible 'ring found to 

 be eight inches up the rod, evidently proving the rod to have 

 been forced into the cylinder that distance, showing, also, a 

 compression of about one per cent. (6) We have seen, by 

 repeated experiments, that, to be able to produce this degree 

 of compression, three per cent, must be pumped into the 



present than can exist in the liquid state, (as was the case in the experiments 

 of DeluCj) there is every reason to suppose that it possesses the .physical 

 properties of a liquid, and has as little compressibility as the water with 

 which it is united. Accordingly, Mr. Canton found that water was no more 

 compressible when saturated with air, than when deprived of it by boiling. 

 • — M. Haiiy, (Traite de Physique, 1. 1 98.) although he denies that water is 

 compressible in any appreciable degree, at the same time justly appeals to its 

 power of conducting sound, as an evidence that it is in fact an elastic fluid. 



(b) By calculating the solid contents of the piezometer, and of that part of 

 the rod which was forced into it, the real compression will be found to have 

 been only one-half per cent. There is reason to believe that the error lies 

 here, rattier than in the dimensions given at the beginning of the article, as 

 the supposition that the compression was one-half per cent, harmonizes with 

 the statement afterwards made, that the apparatus last employed gave the 

 ftoitipression twice as great as the first. 



