Observatory, determined from the Magnetograph Curves on during the year 1892. (19° + West.)

TABLE III.-Hourly Means of the Horizontal Force at Falmouth (corrected for Temperature) on Five selected quiet Days in each

TABLE IV.—Diurnal Range of the Falmouth Horizontal

+00001+00002+00002+00004+00005 +00006 +00007 +00003-00006 -00009 00021-00021

Annual Mean.

+00005 +00004 +00004+00004 +00005+00004 +00001 —00006 —·00015 00020-00026 00022

1 Approximate values.

NOTE.-When the sign is + the

Observatory as determined from the Magnetograph Curves.
Month during the year 1892. 0·18000+(C.G.S. units).

Force as deduced from Table III. (C.G.S. units.)

00014-00006+00002+00006+00009+00013+00016+00016+00016+00015+00013+00012

Winter Mean.

-00016 -00009 -⚫00004

-00001+00001+00005+00008+00010 +00009+00007 +00008+00009

-00015

Annual Mean.

00008+00001+00003+00005+00009+0001200013+00013+00011+00011+00011

reading is above the mean.

TABLE V.-Magnetic Intensity. Falmouth Observatory, 1892.

TABLE VI.-Observations of Magnetic Inclination.

Falmouth Observatory, 1892.

Experiments for Improving the Construction of Practical Standards for Electrical Measurements.-Report of the Committee, consisting of Professor CAREY FOSTER (Chairman), Lord KELVIN, Professors AYRTON, J. PERRY, W. G. ADAMS, Lord RAYLEIGH, and O. J. LODGE, Drs. JOHN HOPKINSON and A. MUIRHEAD, Messrs. W. H. PREECE and HERBERT TAYLOR, Professor J. D. EVERETT, Professor A. SCHUSTER, Dr. J. A. FLEMING, Professors G. F. FITZGERALD, G. CHRYSTAL, and J. J. THOMSON, Messrs. R. T. GLAZEBROOK (Secretary), W. N. SHAW, and T. C. FITZPATRICK, Dr. J. T. BOTTOMLEY, Professor J. VIRIAMU JONES, Dr. G. JOHNSTONE STONEY, Professor S. P. THOMPSON, and Mr. G. FORBES.

APPENDIX

1. Supplementary Report of the Electrical Standards Committee of the Board of Trade

PAGE

129

II. Experiments on the Effects of the Heating produced in the Coils by the
Currents used in Testing. By R. T. GLAZEBROOK
III. On Standards of Low Electrical Resistance. By J. VIRIAMU JONES 137

136

THE work of testing resistance coils at the Cavendish Laboratory has been continued. A table of the coils tested is given. They have all been 'ohms,' as defined by the resolution of the Committee given in their last report, and since adopted by the Board of Trade Committee on electrical standards in the following form:

The resistance offered to an unvarying electric current by a column of mercury at the temperature of melting ice 14-4521 grammes in mass, of a constant cross-sectional area, and of a length of 106.3 centimetres, may be taken as 1 ohm. The relation between the B.A. unit and the ohm is the following: