Sessional_Paper_1903 — Page 117

33

17. The observations of magnetic declination and horizontal force published in tables XI. and XII. were made with magnet No. 55 on Kew pattern unifilar magnetometer ELLIOT BROTHERS No. 55. The dips were observed with dip-circle Dover No. 71.

2

The methods adopted in making observations and in determining and applying the corrections are explained in Appendix G of Observations, and Researches made in 1885-"On the verification of the Unifilar magnetometer ELLIOT BROTHERS No. 55." The value of log K used was 3.44907 at 25°. The value of P was 7.04. The mean value of the magnetic moment of the vibrating needle was 577.27.

The times of vibration exhibited in Table XII. are each derived from 12 observations of the time occupied by the magnet in making 100 vibrations, corrections having been applied for rate of chrono- meter and arc of vibration.

The observations of horizontal force given in Table XIII., are expressed in C.G.S. units. The vertical and total forces have been computed by aid of the observed dips.

The Honourable

The Colonial Secretary

&c.,

I have the honour to be,

Sir,

Your most obedient servant,

&C.,

&c.

F. G. FIGG,

Acting Director.