246 PROF. EDWARD HULL, ON THE ABNORMAL CONDITIONS 
of the molecules in each case. In solids the molecules are not 
in contact, and consequentiy pressure only forces them closer 
to each other, “ but in liquids, the molecules are within the 
spheres of each other's action; and each molecule is free to 
adjust its mean position under the influence of surrounding 
molecules.” This, at least, is Alfred Daniel’s interpretation of 
the phenomena. ‘ 
3ut whatever be the true explanation of the difference 
between fluids and solids as regards incompressibility and the 
veverse—the experiments shown in Bramah’s hydraulic press, 
and by Francis Bacon seem to confirm both the above state- 
ments. In the former case a ball of iron was filled with water 
at 3°9° Cent. and closed. It was then subjected to great 
pressure; but the water forced itself through the pores of the 
iron, and appeared on the surface as vapour. In the latter 
case, a Shell of lead was filled with water and compressed ; the 
water oozed through the lead in drops and beads on the surface 
of the shell, showing that the iron and lead are porous; while 
the water resisted compression, up to the bursting point of the 
shell and ball. 
But however the question of incompressibility might be 
investigated by the aid of experiments in the laboratory it is 
surely set at rest by observations in the region of physical 
phenomena itself. It may be impossible to imagine that water 
like other substances in nature cannot yield to any conceivable 
foree—but for all practical purposes, the fact remains that it is 
incompressible; as it remains fluid at the lowest depths of the 
ocean yet touched by the soundings. Depths of 2,000 fathoms 
and upwards have been sounded in waters of the North Atlantic 
at a temperature of 2° to 3° C. (87° to 39° Fahr.)} and living 
forms have been brought up from the bottom. What the 
pressure on the lowest strata of the water may be I cannot 
venture to say; it must be some thousands of tons per square 
foot, but it is insufficient to consolidate the water even at a 
temperature approaching freezing point. Now just imagine for 
a moment compressible water. What would be the state of the 
ocean under such conditions even were the degree of com- 
pressibility of the slightest ? Evidently, that after the weight 
* Principles of Physics, p. 254, 3rd edit. 
+ Principles, p. 220; we are ‘not told the amount of pressure, or the 
thickness of the ball and shell, but we may assume they were both 
sufficient to satisfy the experimentalists up to bursting point. 
t Wyville Thomson, Depths of the Sea, p. 322, Plate VI. 
