686 
Proceedings of the Royal Society 
difficulty in achieving the thermal adjustment by the aid of a 
water jacket and a delicate thermometer. To facilitate the requisite 
thermal adjustment, I propose, in a new instrument of which I 
shall immediately commence the construction, to substitute for the 
brass tube a long double girder of copper (because of the high 
thermal conductivity of copper), by which sufficient uniformity of 
temperature along the spring throughout the mainly effective por- 
tion of its length and up to near the sighted end, shall be secured. 
The water jacket will secure a slight enough variation of tempera- 
ture to allow the absolute temperature to be indicated by the ther- 
mometer with, I believe, the required accuracy. 
2. Measurements of the Electro-Motive Force of a Constant 
Yoltaic Cell with Moving Plates. By A. P. Laurie, 
B.Sc., B.A. 
3. Note on the Formation of the Hectocotylus in Kossia. 
By W. E. Hoyle, M.A. 
4. On some Definite Integrals. By Professor Tait. 
5. On Alterations in the Electric Conducting Power of 
Alloys at their Melting Point. By Harry Bainy, M.A., 
and E. D. Clarkson, B.Sc. (Plate XXYI.) 
The electric conductivity of metals has been observed to change 
very greatly at their melting point, the resistance being in many 
cases nearly doubled when the metal is fused. The experiments 
recorded in the following communication originated in an attempt 
to investigate more fully into this fact. The metals chosen for the 
first observations were tin and lead, both of which have their melt- 
ing points at temperatures that can be readily obtained. 
At first we endeavoured to take the resistance, at various tem- 
peratures, of a column of metal having a definite cross section and 
length, by means of a Wheatstone’s bridge. For this purpose glass 
tubes were employed, which were placed horizontally in a hot-air 
bath, where they could be raised to a temperature considerably above 
