268 Mr Perkins on the compression of' Water and other Fluids 



its position, after being pressed upwards on the tube, so as to 

 serve as a register of the degree of compression that has been 

 effected. The piezometer is now filled with water, and with 

 its register and disk it is placed in a phial containing a small 

 quantity of quicksilver. It is next placed in the receiver of 

 the compressing press, and after the proper pressure has been 

 applied the piezometer is removed, and the indicating spring is 

 found raised in the tube more or less, according to the power 

 employed. 



The greatest amount of which this apparatus admitted was 

 1000 atmospheres, being equal to 14,000 pounds to the square 

 inch. With this apparatus Mr Perkins obtained the following 

 results, which are the means that we have calculated from his 

 tabular numbers. The column of water is 190 inches, and the 

 numbers in the tables are the compression produced by the 

 number of atmospheres around. 



Atmospheres. Compression. Atmospheres. Compression. Atmospheres. Compression. 



If we make the number of atmospheres the abscissa of a curve, 

 and the compressions its ordinates, it will be found that the 

 curve approximates to a hyperbolic one. 



In order to estimate higher degrees of compression, Mr Per- 

 kins constructed another piezometer eight inches long, ground 

 internally perfectly cylindrical, and stopped at its upper extre- 

 mity with a flat disk of glass cemented into it. This tube he 

 filled with water, and subjected it to a pressure of 2000 atmo- 

 spheres. After repeating this experiment a great number of 

 times, the average result was, that the column of water eight 

 inches long was compressed two-thirds of an inch, or one-twelfth 

 of its length. If we reduce this result to the scale of the pre- 

 ceding table, we shall find it to be 15.833, as there inserted. 



