372 Mr. Christie on the diurnal deviations of the 
of another needle, which I call No. 2. This needle is 4 .3 
inches long, nearly of a similar form to No 1, and, like it, 
balanced by an agate cap on a fine point. The rim of the 
compass-box is accurately divided into degrees, so that I can 
read to the nearest 5'. The observations with this needle 
were commenced on the 4th of May, and continued without 
much interruption until the 18th : these I shall first describe. 
Two bar magnets, each ten inches long, .95 inch wide, and 
,4 inch thick, but not by any means powerful, were placed 
on the same horizontal table as the compass, with their poles 
towards those of the needle of the same name. As my ob- 
ject at first was, to observe the changes at points differing 
considerably in their positions with regard to the north and 
the south, I did not adjust the magnets in the meridian, but 
each somewhat inclined to it, the nearest end of each being 
n-575 inches from the centre of the needle. I had taken the 
time of vibration of the needle previously to applying the 
magnets, but lost the memorandum of it ; however, when 
they were removed, at the conclusion of the observations, it 
made ten vibrations in nineteen seconds. 
My first object was, to determine the three points at which 
the needle would remain stationary, after being agitated ; that 
is, the three points of stable equilibrium . , and likewise the three 
points of instable equilibrium : I determined them as under : 
4th of May, 5 h 20“ A. M. 
At < 
S 55 ° 3 o' W 1 
S 55 40 w J 
S 59 O 
S 59 45 
N 20 50 
N 20 10 
E 
E 
E 
E 
} 
<0 bo « 
3.S-H 
oj 
S-O & 
o 
a> +-> 
c 2 
qjG 
a. 2- 
4-< 4J *\ 
^ 03 T3 
O 4-» <l> 
c " ts 
f South. 
[West. 
0 J 
f South. 
| East. 
„ f East. 
I § 'll I North. 
