44 
THE EEY. STEPHEN J. PERRY ON THE MAGNETIC 
Table XI. 
Station. 
Date. 
G. M. T. 
Error. 
Daily iate. 
Stonyhurst Observatory 
London, Lrodsham 
July 2(i 
Aug. 7 
h m 
m s 
+0 50-14 
+ 1 130 
s 
+0-57 
+ 1-8 
Paris Observatory 
., 11 
3 30 
+ 1 15-63 
+0-66 
Brest Observatory 
17 
2 15 
+ 1 31-71 
18 
2 15 
+ 1 32-88 
+ 1-17 
„ 10 
2 15 
+ 1 34-05 
+ 1-17 
Bordeaux, Depots des Chronometres . . . 
„ 20 
1 13 
+ 1 200 
Abbadia Observatory 
Sept. 2 
„ 0 
17 
+ 1 37 -7 
+ 
+ 1 51-5 
+0 28-0 
+0 34-35 
+2 15-58 
+2-18 
small 
+0-02 
+ 1-0 
Toulouse Observatory 
London, Lrodsham 
21 
Stonyhurst Observatory 
30 
March 14 
+0-61 
At Toulouse the chronometer was only compared as to rate by the Director of the 
Observatory, the absolute times of comparison not being- registered. 
Altitudes of the sun were taken at nearly all the stations with Cooke’s small altazi- 
muth, but these were only used as a check on the above results and for intermediate 
stations. These direct determinations of the rate of our instrument were exceedingly 
useful, from showing us that the two principal disturbances probably do not interfere in 
the least with the results obtained, since the first took place between Poitiers and Bor- 
deaux, and the second between Amiens and London. 
In the following Table of observations the first line of azimuths at each station was 
read on the theodolite circle, and the second line on the unifilar. The centre division 
of the magnet was always made to coincide with the centre line of the telescope, except 
at Cannes, where it was 0-1 div. to the apparent left. The zero of the scale of the col- 
limator magnet was + 7-2 div., each scale-division being =2' 9"'805. 
At Abbadia the azimuth of the mark A, i. e. the Biarritz Lighthouse, was accurately 
determined by M. Antoine d’Abbadie, President de la Societe Meteorologique de 
France. 
