54 PROFESSOR C. V. BOYS ON THE 
A =150°9, Pointer at 24520 Drew air once. 
= O7 

24493 No time correction worth making, 

Times of Transit. 
hey am s. 
14 20 36°34 —> g., time mark, 14h. 21m. 
22 3el: se: 
23 49-7 4-02 —-» -02 early. 
25 26:58 —-06 ~<— -06 late. 

27 = 301 —> v.g. Castle mark. 
28 39°68 pa 
Interval. 
Al 32:7 <—— Time mark, 14h. 42m. Castle mark. 
43 9:42 — v.g. 
Amplitudes. Points of rest. 
(44 46-1) <— Pendular oscillation. 
26915 — 26 7} 2 244.91:2 
46 22°87 4406 & 
22505 —22 | All bad with ane 24488 
47 59-42 \ pendular dis- 3690 = = 
26199 — 26 | turbance S| 24486°6 
(49 36-1) Bad transit 3101 5 8 
23106 — 24 J a 
51 12°48 2601 — 
25698 — 25 Castle mark. 
52 49°35 T'ransit. 
If the pointer had been found to have been definitely out of place, but, of course, 
by a small amount, I should have corrected the observed times of transit by a series 
of alternate + and — quantities, calculated from the amplitude, period, and error of 
position. In the present case, owing to disturbance, the point of rest showed an 
uncertainty of nearly half a division, and I could not be sure from these observations 
that the pointer was not placed that much in error. On the other hand, after 
subtracting the time of each transit from that above, the series of observed half 
periods show a small, fairly regular, increasing and alternating second difference, 
which is in itself a sign that the pointer was very slightly on one side of the true 
position of rest. If no account is taken of this, the half period deduced from the 
first and last observation is found to be 
96°650 seconds ; 
from the first observation marked g to the last marked g it is 
96°649 seconds ; 
