98 AKSEL S. STEEN. TERRESTRIAL MAGNETISM. [NORW. POL. EXP. 
OBSERVATIONS OF VIBRATION. 
The manner, mentioned on page 67, in which the time of vibration 
for magnet V or VI was determined, gives, as will be understood, 11 separate 
determinations for each series of vibrations, of the time for 100 vibrations, 
all of which are given in the table. On rare occasions, the attempt to note 
the moment of an expected passage of the magnet over the middle line of 
the seale, has failed, and only 10, instead of 11, determinations of the time for 
100 vibrations have been obtained. Once a series of observations of the 
time for 101 vibrations has been made, twice of the time for 130, and once 
of the time for 160 vibrations. Investigations as to the extent of the effect 
produced by the proximity of the revolver upon the values for the hori- 
zontal intensity deduced from the vibration observations, were made on the 
20th April, 24th May, 4th and 26th July, and 20th August, 1895. On April 
20th, the vibration box stood upon a stone slab frozen firmly into the ice. 
During two series of vibrations with magnet V, and two with magnet VJ, the 
revolver lay east and west, 4 paces directly north of the magnet; while during 
one series of vibrations with magnet V, and two with magnet VJ, it was 
laid aside. The values for the horizontal intensity, H, calculated from these 
7 series of vibrations, are as follows: 
Magn. V Magn. VI 
a b a b 
The revolver | The revolver | The revolver | The revolver 
in its place laid aside | in its place laid aside 
April 20. 11" 37" a.m.] — 0:04695 
12 18 p.m. 
12 39 004620 
3 23 
3 46 
4 10 
4 37 
Mean "046 0:04596 0°04526 
