FEBRUARY 25, 1897 | 
NATURE 387 
oO 
In ‘The Constitution and Functions of Gases,” by 
Severinus J. Corrigan, an attempt has been made to 
advance a new dynamical theory of gases, and to do 
away with the necessity of a continuous ether for the 
transmission of radiation through space. 
In the ordinary kinetic theory of gases, which has 
been worked out so fully by Maxwell, Clausius, and 
others, the molecules of which the gas is composed are 
conceived to bein continual motion among one another, 
each molecule moving through a mean free path, while 
pressure on a surface is due to the continuous bombard- 
ment of the molecules. The theory which Mr. Corrigan 
advances is as strictly dynamical as the ordinarily 
accepted one, butis based on quite different assumptions. | 
The molecule, instead of being in continual motion to 
and fro, is at rest, but is made up of a large number of 
atoms, which revolve in orbits, approximately circular, 
round the centre of the molecule with enormous 
velocities. 
The atoms themselves are supposed to be “perfectly 
elastic, incompressible, spherical solids which are ar- 
ranged primarily in duads or combinations of two, and 
the atoms of each duad combination are mutually 
attracted by a force in each atom, which force, like that 
of gravity, varies inversely as the square of the distance 
between the members of the duad.” These two atoms 
are endowed with opposite polarity of some kind, 
probably magnetic, and are analogous to a system of 
binary stars of equal mass and volume, and their motion 
is governed by the laws of motion of celestial bodies. 
The molecule is supposed to be built up of an enormous 
number of these rapidly rotating magnetic couples with 
the planes of their orbits in all directions, so that the 
molecule is a hollow shell of gas, the surface atoms of 
which are in extremely rapid motion round the centre of 
the molecule. 
The pressure of the gas is assumed to be proportional 
to the mass of the gas and the angular velocity or 
vibration frequency of the atom, while a change of 
pressure alters the diameter of the atomic orbit. In 
a very rare gas, therefore, the diameter of the atomic 
orbit is immensely greater than at ordinary atmospheric 
pressure. 
Proceeding on.these assumptions, the author certainly 
makes his theory satisfactorily account for some of the 
properties of gases. Great stress is laid on the theoretical | 
deduction, from the hypothesis, of a law of radiation of 
identically the same form as the empirical formula of 
Dulong and Petit. The value of the constant is also 
deduced, and this is in complete agreement with the 
experimental value. 
The ether, instead of being the continuous medium 
demanded by physicists, is supposed to be molecular and 
discontinuous—practically a gas of excessive tenuity. 
A large amount of space is devoted to the consideration 
of a mode of transmission of radiation, from molecule to 
molecule of the gaseous ether, with the velocity of light ; 
but so many difficult assumptions are made in the 
course of it, that the explanation, though plausible, is not 
at all satisfactory. The impulse which the revolving 
atom receives from contact with a vibrating surface is 
supposed to be handed on from molecule to molecule 
with the velocity of light ; but it is not clear why an atom 
NO. 1426, VOL. 55] 
of an adjacent molecule should always be in exactly the 
right position for the transmission of an impulse. 
It will be of interest to mention a few of the results 
which the author deduces from his equations. The 
number of atoms in the atmospheric molecule is calculated 
to be about 10", and the orbital velocity of the atom of 
air at atmospheric pressure and temperature 500 million 
miles per second. The number of atoms per cubic 
centimetre of the gas agrees very nearly with the results 
deduced by Lord Kelvin and others. The density of the 
luminiferous ether (air = 1) is about 3:107!", and the 
diameter of a molecule of the ether ‘oo2 inches. 
As a consequence of the theory the conjugate atoms 
would be disrupted at an absolute temperature of 6679° 
Fahrenheit, and the author considers that disruptive 
electrical discharges, such as from an induction coil or 
in lightning, do break up the molecules, and it is the 
recombination of the dissociated atoms which causes the 
crash of thunder after the lightning flash. 
The most unsatisfactory portion of the book is where 
the author endeavours to explain electrical phenomena, 
like atmospheric electricity, and natural disturbances, 
like tornadoes, by his theory of gases. A table of the 
dimensions and weights of the atoms of the molecules of 
the air and ether, which are deduced from the equations, 
is given; while a supplement is added to the book, 
deducing the same results in a different manner, and 
various theories are advanced in regard to the solar 
corona and astrophysics generally. 
Though one may not agree with many of the author's 
assumptions, the fact remains that an interesting dy- 
namical theory has been advanced which accounts for some 
phenomena not explained by any other theory ; and for 
those who may be interested in speculations in regard 
to the nature and constitution of the gases and the 
ether, the book is well worth reading. Has 
IMPRESSIONS.OF OUT-DOOR NATURE. 
A Year in the Fields. Selections from the writings of 
John Burroughs. With illustrations from photographs 
by Clifton Johnson. Pp. ix + 220. (London: Smith, 
Elder, and Co., 1896.) 
A-Birding on a Bronco. By Florence A. Merriam. 
Illustrated. Pp. x + 226. (Boston and New York: 
Houghton, Mifflin, and Co., 1896.) 
Summer Days for Winter Evenings. 
ford, F.L.S. Illustrations by John Williamson. 
ix + 274. (London: John Macqueen, 1896.) 
By J. H. Craw- 
Pp. 
HE highest merit in any book of natural history is 
that it contains new and valuable information. 
Such books are often, but by no means inevitably, dry. 
Mr. A. R. Wallace may be named as one living writer 
who gives us new and valuable matter in a thoroughly 
readable form. Without being absolutely original, a 
book may yet be well worth writing if it contains a good 
deal of useful information served up in an attractive way. 
Then we come to the books which are attractive but not 
useful, and so tothe books which are neither one nor the 
other. 
None of the books»before us belong to either the 
