370 Proceedings of the Boyal Society of Edinburgh. [Sess. 
parallel tubes in which rods slid, the rods and tubes being mounted verti- 
cally 2 cms. apart. The lower ends of the tubes were attached to the 
opposite plates of a condenser C, the capacity of which was 50 cms. The 
Oscillator 
Fig. 1. 
upper ends of the rods were joined by a thermo-couple T, from which wires 
led to a sensitive d’Arsonval galvanometer G. 
The thermo-couple, which fulfilled its purpose very well, is shown in 
H 
o 
B 
D xe 
K 
Fig. 2. 
the second diagram. A, B are the ends of the rods viewed from above. 
ATD is a short piece of thin platinum wire, BTF a short piece of thin con- 
stantan wire, both of which are held together by a very small drop of 
