Appendix. 311 
magnetic observations taken at Cape Adare during 1899-1900 
involved the three elements Declination, Inclination and Intensity, 
and were conducted in an open Lapp tent with great personal 
inconvenience, sometimes even at a temperature of — 25? C. 
This tent was situated at a distance of about 2,000 yards from the 
base of a volcanic and highly magnetic range of mountains, which 
undoubtedly had considerable influence upon the magnets. ‘The 
disturbances due to the occurrence of the aurora were also very great, 
so that very few of the observations taken with the Unifilar Magne- 
tometer are entirely free from its influence. On account of the weak 
horizontal intensity in the deflexion observations for the moment of 
the vibrating magnet, distances 39 cms. and 52 cms. had to be used 
instead of 3o cms. and 4o cms., and as we had no correction to our 
deflexion bar for these distances, it was not possible to reduce the 
observations on the spot. In the vibration observations, every third 
transit was observed instead of every fifth, and in many cases it was 
impossible to observe torsion of the suspension thread on account 
of the agitation of the magnet. The horizontal force derived from 
a single observation taken on May ттїһ, 1899, assuming errors at 
39 cms. and 52 cms. to be same as at до cms., gives *o4086 C.G.S., 
dip at same time being — 86° 35' 20", and declination 55° 46 55" E. 
at 5.30 P.M. 
The mean of some forty dip observations taken at Cape Adare 
gives — 86? 34' 13", while the mean of some fifty declinations 
gives 56° 2' o" E. The diurnal variations of magnetic conditions at 
Cape Adare appear to be very great, but the sudden and relatively 
large disturbances make the determination of the normal daily 
variations a difficult matter. The presence of large masses of basalt 
and other magnetic rocks, which magnetised by the induction of the 
earth's magnetic field, must deflect the magnet, and consequently 
the true magnetic declination may be assumed to be in error. 
Although it is not possible to eliminate errors due to this source, one 
may presume them to be constant. On April roth, r899, the 
declination was observed every twenty minutes right through the 
twenty-four hours, The maximum declination occurred at 4. 5 A.M., 
and the minimum at a little after noon, the difference between 
maximum and minimum being 3? 2' 5". Again, on January 2nd, 
1900, declination was observed every fifteen minutes. The maximum 
occurred at 6 P.M., and the minimum a little after noon, the 
difference between maximum and minimum being 1° 38' то. The 
change in declination takes place in long oscillations or system of 
pulls from 15 to 20 scale divisions to right and left of the centre, the 
