312 Proceedings of the Royal Society 
position. This system may aptly be compared to that produced 
within the wire cube, and previously described. The analogy of 
the two systems may be further carried out by inserting one or 
more small bubbles in the centre of the system, which will, accord- 
ing to the form of the cone employed, assume a form approaching 
to that of a cube, and therefore analogous to the system shown in 
figs. 4 and 5 of Plate xxxiv., or to that of a pyramid (perfect or 
truncated), and therefore corresponding to the systems in 10 and 
11 of the same plate. 
The paper contains also some experiments on the motions of films 
when brought in contact with surfaces of glass under certain con- 
ditions. Thus, if a film be formed on the mouth of a wine-glass 
by dipping it in the solution, and be then covered over by a watch- 
glass of more or less convexity, so long as no contact is established 
between the film and the watch-glass no change will take place. 
But let the wine-glass be inverted so as to bring the film into a ver- 
tical position (the watch-glass being meantime kept firmly in posi- 
tion by the thumb), the film will now attach itself to the watch- 
glass at its lowest margin, and will run up its inner surface, de- 
scribing thereon a series of curious curves. The upper part of the 
film will at the same time retreat down the inner surface of the 
wine-glass, and form a hollow segment of a sphere. 
The cause of the phenomenon is the existence of a drop of the 
solution which enters the wine-glass in the operation of dipping, and 
remains at its bottom, and which, when the glass is inverted, runs 
down as far as its margin, and there comes in contact with the 
margin of the film. A connection is thus produced between the 
film and the watch-glass, which originates at a single point, but 
quickly extends in the manner mentioned. A variety of further 
experiments may be made on the film thus produced, several of 
which are described in the paper. 
The last part of the paper consists of an account of some mis- 
cellaneous experiments chiefly on the tenacity of films when 
brought in contact with one another, or with surfaces of fluid, and 
then drawn apart, and the forms of the curves which in such cir- 
cumstances they assume. 
The paper is illustrated by a number of coloured sketches, done 
for the author by a lady residing near him at Melrose, who also 
