C 541 } 
XXXII. On the progressive compression of water by high degrees 
of force , with some trials of its effects on other fuids. By 
J. Perkins. Communicated by W. H. Wollaston, M. D. 
V.P.R.S. May 25. 
Read June 15, 1826. 
The apparatus suggested by me in a paper read before the 
Royal Society the 22nd of June, 1820, on the compressibility 
of water, having now been completed, I will first describe its 
construction, and then give an account of the experiments 
already made with it. 
Fig. 1. In the accompanying drawing, Plate XX. is a 
view of the compressing machine, and fig. 2 is a sectional 
view of the same, of which the following is a description. 
A, is a cylinder of gun metal, the length of which is 34 in- 
ches, and its external diameter 13 % inches ; B, is the receiver 
of the compressor, being i-§- inch in diameter, and 29 inches 
long ; C, is the barrel of a steel pump, 8i inches long and 
inches diameter, on the outside of which a screw is cut 
7 inches in length, by which it is finally united to the com- 
pressor ; D, is the chamber or caliber of the pump, T -V °f an 
inch in diameter, and continuing of the same size throughout 
the whole length, excepting a conical enlargement at the 
bottom and top of the pump ; the bottom cone receives the 
valve B when opening inwards ; F, the piston or plunger of 
steel, most accurately fitted to the bore of the pump, having 
its lower extremity hollowed out to a semi-elliptical cup, 
with a very thin edge, the expansion of which during the 
MDCCCXXVI. 4 A 
