88 Mr. R. J. Moss, 
to the maximum production of vapour. Mr. Stoney’s explana- 
tion not only removes this anomaly, but demands the compara- 
tively low temperature of the spheroid as an essential condition 
of the phenomenon, since the existence of the layer of polarized 
air or vapour by which the spheroid is supported, requires the 
proximity of a cool surface, in order that the velocity of the 
gaseous molcules moving from this surface may be much less 
than that of the molecules which move towards it from the adja- 
cent hot surface. 
Mr. Stoney suggested to me the possibility of maintaining 
spheroids on liquid surfaces of the same substance by ensuring 
that the floating drop shall continue cooler than the liquid under- 
neath, and by otherwise removing the causes which occasion its 
shipwreck. Commercial ether readily adapts itself to the re- 
quired conditions. After a series of experiments I have adopted 
the arrangement shown in the figure as one which successfully 
accomplishes the desired objects. 

A thin glass tube about 15 mm. in diameter and 12 em. long 
having a spout-like limb about 7 mm, in diameter and 7 cm. in 


