142 THE ROYAL SOCIETY OF CANADA 
in declination no extended series were obtained and results deduced 
served more as a check on the total force observations with the Dip 
circle. 
At stations occupied in Hudson Straits Intensity observations 
were made with both instruments and the results agreed to within 
-002 C. G. S. units. 
Latitudes were determined by meridian and circummeridian ob- 
servations of the sun and longitudes by chronometer. Time observa- 
tions were generally made by sextant and artificial horizon observations 
on the sun, but were also obtained in conjunction with Azimuth observa- 
tions with the theodolite of the magnetometer, these observations being 
invariably taken on the sun at or near the prime vertical so long as the 
altitude of the sun was greater than 5 degrees, and in both morning 
and afternoon whenever the opportunity was afforded. Chronometer 
comparisons were made at the Quebec observatory both at the beginn- 
ing and end of the cruise. 
The Instrumental outfit used during 1910 consisted of Dover Dip 
Circle No. 205, which was secured through the courtesy of the Director 
of the Department of Terrestrial Magnetism of the Carnegie Institute 
of Washington, D.C. D. T. M. C. I. Magnetometer 15, Molyneux 
chronometer No. 3332. 
Dip circle, 205 is also a total force instrument but is only provided 
with one distance. From observations made at Agincourt on Sept. 28, 
and Oct. 18, 1910, the value of log C was determined to be 9-57764. 
The correction to reduce dip to Agincourt Standard is -0-8, but this 
was not applied as it varies with Magnetic latitude. 
Magnetometers of same type as D. T. M. C. I. No. 8 and 15 have 
been fully described by J. A. Fleming.! The constants for Magneto- 
meter 15 supplied with the instrument are:— 
For r= 19-9959 cm. at 20 cent. log C—6-40596 
— 7459946 em. =“ REC 6-11 246 
r=—27.9992 cm. “© * |* | 4 C==5-06355 
for t, log C= log C,, + (20-t) 0-0000235 
Temperature coefficient q = 0-000451 
Induction coefficient p=2-95 
Distribution coefficients P — + 7-288 Q— + 84.47 
Moment of Inertia. log K at 0° cent = 1-81816. 
1 scale division magnet marked 15 L = 2’-00 
Observations for comparison with Agincourt Standard were made in 
April, September and October 1910 from which the following results 
were obtained :— 
Terrestrial Magnetism, Vol. XVI., No. 1. 
