TRANSACTIONS OF THE SECTIONS. 
63 
those of the planets, the particles of the zodiacal light and the satellites of our solar 
system, and such rotatory motions as the central and other masses are known to 
have, all chiefly in one direction. 
In considering the question whether all the heat and motion existing in matter 
have their origin in that action by which their amount is at present being increased, 
it is shown that, unless their entire actual energy exceeds a certain definite limit, 
namely, the value of the whole potential energy of gravitation that would be spent 
in drawing all the particles of matter from a state of infinite diffusion into their 
present positions, it is quite possible they may be so produced ; or that the potential 
entry/of gravitation may he in reality the ultimate created antecedent of all the motion, 
heat, and light at present in the universe. 
On the Motion of Fluids ; a remarkable variation in the great Elementary 
Law of the ratio between Pressure and Velocity. By William Petrie, 
Woolwich. 
One of the most universally recognised laws of the flow of fluids is, that the 
velocity of flow through an aperture from or to a containing vessel varies as the 
square root nf the pressure, and this law is evidently a necessary corollary from 
the first principles of dynamics. 
The present paper is to call attention to the fact, that when the passage through 
which the fluid (as air or water) is forced, consists of a single check, such as a 
mple hole, the above law holds precisely true ; yet when the passage consists of an 
indefinitely numerous consecutive series of checks, such as a tube containing sand, 
the velocity of flow varies in the direct arithmetical, ratio of the pressure ; and that 
in the intermediate cases of a few consecutive checks being placed to retard the flow 
uf the fluid, the law seems to follow various intermediate ratios accordingly. For 
the rase of about 30 consecutive chocks causes the law of variation of velocity to be 
06 the J power of the pressure. 
Whether this important law be altogether new or not, the author feels it to be 
ino.st perplexing; it being, apparently, contrary to the most indubitable deductions 
from the above-named great elementary law. For it is to be observed that it is no 
question regarding the absolute velocity of (low through the checking passage, under 
a certain pressure of fluid; that might well be regarded as incalculable, and not 
Accurately amenuble to any discoverable rules in such u practically complex dyna¬ 
mic 11 ' condition as the flow of air or of a liquid through a mass ot sand. But the 
question regards the effect uf a simple variation of pressure, ceteris paribus, in which 
TWiatiou, therefore, all the directions and counteractions of currents, however 
complex, must remain relatively precisely the same, the velocities of all being 
necessarily affected in precisely the same ratio. The subject has many ramifications 
J "flnch the author hopes in some degree to follow up. 
On u Method of Computing the Absolute Volume of the Ultimate Particles of 
Liquids. Jiy J. J. Watersten. 
!“ paper certain theoretical views regarding the mutual action of particles of 
l iquid, especially near its free surface, were brought forward, according to which a 
nation between the IaU ..r heat of its vapour and the contractile tendency of its 
surface was established in terms of the dimensions of its atoms, supposed by the 
I”, ^ to kHinite. Experiments on the forms and dimensions of drops of water, 
u the bearing of water in capillary tubes, exhibited by diagrams traced from pho- 
c r »pns, were described, from which thecapillary tension of a free surface of water 
estimated. A comparison of this result with data regarding the mechanical 
'P tt °* steam afforded by M. Regmullt and Mr. Joule by experiment, led the 
C0 °clusion that the number of atoms in a cubic inch of water is about 
q a o the cube of 216,000,000 ; or, that there are only as many atoms of water 
mass of th e liqujj equal in volume to a billiard ball, as there are of such volumes 
the whole bulk of the earth. 
and tl u" between the capillary tensions of different liquids, their atomic weights, 
c latent heats of their vapours, was shown to follow from the theory; a Q d it 
