132. Mr. C. A. Chant on the Variation of Potential along 
long, and no attention was paid to polishing the knobs. 
That portion of the condenser circuit forming the primary 
of the transformer was a single turn of copper wire 6 mms. 
in diameter, bent into a circle of mean diameter 6°8 cms. 
(D, D, fig. 5). The secondary, 
which was within the primary, Fig. 5. 
consisted of 54 turns of heavily 
insulated wire of a total length 
of 99 cms. The diameter of 
the wire and its insulation was 
2°5 mms., and the turns lay 
close together. A vertical 
section, one-half of full size, 
is shown in fig. 5. 
As is known, in this system 
earth connexion is usually not 
made *, but in place of it an 
earth plate is used, intended to balance the antenna and thus. 
give symmetry to the oscillating system. The earth plate 
supplied with the apparatus was a hollow metal cylinder, 
20 cms. long and § cms. in diameter. It was joined to a binding 
post (B) of the transformer secondary by a wire 40 cms. long.. 
When it was desired to join B to earth the cylinder was securely 
bound to a large metal plate, which, along with other metal 
sheets, was connected to the heating-radiator. When em- 
ploying a wire similar to the antenna to balance it, this wire 
was joined to B and, as in the experiments described above, 
was drawn up towards the ceiling. 
In supplying the apparatus the makers stated that it was. 
designed to emit waves of length 10 metres. It was very 
constant in its action and easy to handle. 
An extended series of observations was made with antennz- 
varying from 200 to 1000 cms., and with four different 
attachments to the end B of the transmitter transformer, 
as follows :-— 
A. With cylinder joined by a wire 40 cms. long. 
B. With earth joined to this cylinder. 
C. With a wire similar to the antenna joined to B. 
D. With the end B free. 
A view of the results obtained is given in Table ‘IT. and. 
Pl XI. figs. 6, 7, 85.9. 
On examination it will be seen that the curves obtained by 
the three methods, A, B, C, are hardly distinguishable from 
each other. Those with method D differ from these somewhat. 
* See discussion on a paper by M. Wien, read before the 74 Versamm- 
lung deutscher Naturforscher und Arzte at Carlsbad, Sept. 1902. Phys.. 
Zeit. Oct. 1902. 

