260 Proceedings of Societies . [March, 
A set of Koenig’s forks have been measured with the following 
results, when corrected to 15 0 C. 
A 256 fork measured in May gave 256-309 mean of 19 expts. 
Same fork in June and October. .. 256-310 „ 43 
Another 256 fork 256*306 ,, 12 
A 320 fork ... 320-372 ,, 18 
A 384 fork 384*437 24 
A 512 fork S 12 ^ 1 » 3° 
These forks would be correct at a temperature of about 25® C. 
An old fork of Sir William Thomson’s, made by Marloye, 
gave 255-253 instead of 256. This is the mean of ten measure- 
ments. This fork would he corredt at about 13 0 C. 
Mr. McLeod informs us that the original suggestion of these 
experiments was made by his colleague, Lieut. Clarke, and that 
they carried out the experiments together. 
Physical Society, Annual Meeting , February 8. — Prof. 
W. G. Adams, President, in the chair. 
The following gentlemen were elected as Council and Officers 
for the ensuing year : — President — Prof. W. G. Adams. Vice- 
Presidents — Prof. G. C. Foster, Prof. R. B. Clifton, Lord 
Rayleigh, Dr. Spottiswoode, Sir W. Thomson. Secretaries — 
Prof. A. W. Reinold and Mr. W. Chandler Roberts. Treasurer 
— Dr. E. Atkinson. Demonstrator — Prof. F. Guthrie. Other 
Members of Council. — Capt. W. de W. Abney, Dr. Warren de la 
Rue, Major E. R. Festing, Prof. Fuller, Dr. Huggins, Prof. 
A. B. W. Kennedy, Prof. McLeod, the Earl of Rosse, Mr. G. 
Johnstone Stoney, Dr. Wormell. Honorary Members — Prof. 
G. R. Kirchoff, Dr. J. Plateau. 
Dr. O. J. Lodge read a short paper on a method of calculating 
the curve of temperature in a rod along which heat is being 
conducted. 
Mr. Shoolbred gave an account of eledlric lighting, illustrated 
by diagrams of the most recent magneto and dynamo-dedtric 
machines and examples of the lamps in vogue. The only sur- 
viving magneto-machine is that of De Meriten’s, which is in- 
comparably superior to the older ones of Nollet and Holmes. 
The dynamo-eledtric machines described were the continuous- 
current machines of Siemens, Gramme, Wallace-Farmer, and 
the alternating-current machines of Wilde, Gramme, and Lontin. 
Wilde’s machine is the first of these, or parent machine, and 
Lontin’s so resembles it that the latter cannot be used in Eng- 
land. In these machines the current from a continuous machine 
is passed through a second machine, which yields the alternating 
currents. In Lontin’s machine, also, a number of distindl cur- 
rents are generated in separate circuits, each of which is capable 
of feeding several lights. There is now one in use on the 
Western Railway of France which gives three distindl currents, 
