140 Proceedings of tlte Royal Fhysical Society. 
term " spheroidal." All fluids became spheroidal when re- 
leased from the cohesive attraction of surrounding solids or 
fluids, and their release was due in every case to the inter- 
position of a thin plate of air or vapour between the sphe- 
roidal" globule and the substance over which it floated. It 
was a mistake to suppose that repulsion" took place in 
these cases. The term repulsion" had no meaning in 
physical science. The author then exhibited to the Society 
the production of the " spheroidal" state in fluids by various 
mechanical and electrical contrivances, and explained the 
mode of action of the latter. He then repeated the experi- 
ments of Boutigny by the aid of large and accurately ad- 
justed plates of heated copper, on which globules and plates 
of various fluids rolled and floated without actual contact 
with the metal, and were thrown into various undulatory 
and symmetrical figures, such as crosses, transparent domes, 
toothed wheels, &c., by the intermittent action of com- 
pressed vapour, while forming and escaping from their lower 
surfaces. At a late meeting of the Society Dr Macadam 
had advanced, that the outer shell of the earth was main- 
tained at a considerable distance from its incandescent 
nucleus by the existence of the spheroidal condition" on 
the inner surface of the former. Dr Wright dissented from 
Dr Macadam's theory, inasmuch as it was impossible that 
the shell and nucleus could be maintained at other than an 
exceedingly minute distance by the hitherto observed laws 
of spheroidal action ; that matter, when maintained in the 
spheroidal state by heat, was subject to incessant motion 
and waste from evaporation, which w^ould not only prevent 
the formation of a continuous shell, but would break up or 
distort that shell, if momentarily formed, by pressure from 
within : and that the observed shape of the earth was that 
which a mass of homogeneous inelastic fluid would take 
during rotation ; while a compound mass (such as a fluid 
shell surrounding a fluid nucleus, and separated from it by 
a layer of elastic aeriform fluid) would either break up into 
a ring on rotation, or exhibit a bulging at its weakest parts 
— the poles. This actual agreement between the observed 
shape of the earth and its calculated shape as a homogeneous 
