the compressibility of water. 329 
A machine calculated to avoid loss of pressure from destruc- 
tion of the materials of which it is composed, will be made 
with all convenient speed. This machine being constructed 
with metallic stuffings and flexible metallic pistons, will effect 
a much greater pressure than the hydraulic press, the power 
of which is limited by the animal stuffing now used. It is pro- 
bable, a pressure of from two to three thousand atmospheres 
may be obtained before the metallic piston is destroyed. 
It is expected that this machine will be sufficiently accurate 
to give the exact ratio of the compressibility of water with 
much greater precision than has hitherto been obtained ; but 
the results of farther experiments must be the subject of a 
future communication. 
29, Austin Friars, 
June 6 , 1820. 
