ME. J. E. H. GOEDON ON THE DETEEMINATION OF 
Kew Observatory. 
Observations of Vibration of Magnet n\ p lent to Mr. J. E. H. Gordon. 
Date. 
Number of 
Observations. 
Time of 
commencement. 
Mean time of one 
vibration. 
Torsion of thread 
1 + tL* 
Mean 
Temperature. 
1876. 
b m s 
sec. 
April 11 
1. 
2 43 33 
3-6880 
1-00061 
51-4 
„ 11 
2. 
3 28 41 
3-6868 
1-00067 
52-8 
„ 11 
3. 
4 1 1 
3*6866 
1-00067 
52-7 
„ 13 
4. 
11 6 29 
3-6850 
1-00069 
40-3 
„ 13 
5. 
11 34 26 
3-6858 
1-00069 
42-4 
„ 13. 
6. 
11 49 37 
3-6859 
1-00069 
43-2 
2=0-000178. 
£'=0-000000596. 
2 0 =the correction for the decrease of the magnetic moment of the magnet produced 
by an increase of temperature, and is expressed by a formula of the form — 
correction to t 0 =q(t 0 — t)+q'(t 0 —t) 2 (27) 
t 0 being the observed temperature, and t an adopted standard temperature. 
Vibration Experiments at Pixholme. 
From some preliminary experiments which need not be detailed it was found that 
the time of a half-vibration at Pixholme was approximately 3*693 seconds. 
The following Table gives the time of every 7th passage taking 6-f- and 5 — . 
Set 1 (A). 
April 23, 1876, p.m. 
Passages in -J- direction, 
h m s 
6 22 31 
6 22 55 
6 23 461 
6 24 381 
6 25 30 
6 26 211 
Mean . . 6 24 12-458 
Mean temperature 13 0, 9 C. 
In — direction, 
h m s 
6 22 29 
6 30 201 
6 24 12i 
6 25 4 
6 25 56 
6 24 12-400 
Time of middle negative passage : — 
From + observations . 
From — „ 
Mean . . 
h m s 
. 6 24 12-458 
. 6 24 12-400 
. 6 24 12-429 
I have here altered the Kew notation to suit the letters commonly used in the C.G.S. system. 
