102 Scientific Proceedings, Royal Dublin Society. 
Later, in the year 1876, Dr. Stoney applied his vivid appre- 
ciation of the molecular theory to solve the problem of Crookes’s 
Radiometer and the allied phenomena in a succession of papers 
appearing in the Philosophical Magazine and in the Transactions . 
and Proceedings of the Royal Dublin Society, dealing with 
polarisation stresses in gases. Part of this work was done in 
conjunction with Mr. R. J. Moss, F.C.8. 
Turning to another branch of Dr. Stoney’s investigations in 
this domain of Physics, we must go back to 1867, when a Memoir 
was read by him before the Royal Society, pointing out the con- 
ditions which limit the heights to which the constituent gases of 
an atmosphere extend (‘On the Physical Constitution of the Sun 
and Stars,’ Proc. Royal Society, i868). The considerations 
contained in that paper were, in 1870, extended and brought before 
the Royal Dublin Society in a discourse which embraced an 
explanation of the absence of a lunar atmosphere. Subse- 
quently further notes were brought before the Society; and 
finally, in 1897, in the Transactions of the Royal Dublin Society, 
Dr. Stoney gave a full account of a theory which accounts for 
many observed facts regarding the atmospheres of heavenly 
bodies, e.g. the prevalence of large quantities of light gases— 
hydrogen and helium—in the Sun, the absence of atmosphere 
in the Moon, the apparently arid state of Mars, and his poverty 
of atmosphere, as well as the seemingly abundant atmosphere of 
Jupiter. The almost complete absence of helium and hydrogen 
from the terrestrial atmosphere also received explanation from the 
interesting theory first put forth by Dr. Stoney. 
Other papers dealing with collateral applications of the Kinetic 
Theory, although of much interest, can only be referred to here 
by title. Such are—“<On the Possible Source of Energy required 
for the Life of Bacilli,”’ Proc. Royal Dublin Society, 18938; ‘‘ On 
the Kinetic Theory of Gases regarded as Illustrating Nature,” 
Proc. Royal Dublin Society, 1895, &e. 
The work which Dr. Stoney has done in the Kinetic Theory 
of Gases, considerable as it is, at the present moment, in a com- 
parison of his many achievements, has to yield place to his still 
profounder work on the nature of the internal motions of the 
atom. 
Attacking the problem so long ago as the year 1868, in 
