596 Proceedings of the Eoyal Society 
This experiment was performed on Saturday, January 9, 1886, and 
the period for which readings have been given, and from which 
the determination k — *005 has been obtained, occurred between 
11 a.m. and mid-day of that date. It was attempted again in the 
evening, beginning at 5.30 p.m. Shortly after 6 p.m. the galvano- 
meter was seen to give irregular deflections, even when not included 
in one of the thermo-electric circuits. These deflections continued 
to increase to such an extent that the directing magnet had to be 
shifted to keep the light-spot on the scale. These phenomena 
were found to be due to the disturbed state of the earth’s magnetism 
at the time, for from 7.30 p.m. till 8.30 p.m. on that evening a 
brilliant auroral display took place. Some readings taken at 
8.20 p.m. showed a deflection of the needle through 2° 15' — this 
even when the disturbance was passing off. 
The ratio of the intensity of the magnetic field due to the earth 
alone, to that due to the earth and magnet has since been tested, 
and found to be the arrangement being such that, superposed 
on the field due to the earth alone was another, almost double but 
opposite. 
In all probability the readings, taken immediately before this 
disturbance was noticed, were affected by it ; for, on taking the 
readings from the last two periods in the evening’s work (about 
6.15 p.m,), and calculating the conductivity therefrom, I find it to 
be *011 and *010 respectively. 
As already stated, the period from which the determination 
k = *0 05 was obtained occurred about mid-day, and there is no 
reason to believe that the readings during that period were vitiated 
by the cause which rendered those taken in the evening untrust- 
worthy. 
PEI V ATE BUSINESS. 
The Right Hon. J. H. A. Macdonald, Professor Frederick O. 
Bower, Mr Robert Irvine, Dr G. Sims Woodhead, Mr Arthur W. 
Hare, Mr George Fosbery Lyster, Dr D. Hoel Paton, the Rev. 
George Laing, and Mr William Macdonald were balloted for, and 
declared duly elected. 
