[ 364 ] 
LVII. An Account of Experiments for determining the Length 
of the Pendulum vibrating Seconds in the Latitude of London. 
By Capt. HENRY Kater, F.R.S. 
[Continued from p. 182.] 
Detail of the Experiments. 
Iy the first experiments which were made with the pendulum, 
it has been already observed that the knife edges rested on plates 
of hard steel ; but as these at the conclusion were found to have 
suffered penetration in no slight degree, planes of agate were 
substituted for them, and the results having thus been rendered 
doubtful, were deemed inadmissible. It may not however be ir- 
relevant to remark, that the distances of the knife edges obtained 
by the two methods which have been before described, did not 
differ quite one ten-thousandth of an inch; and, that on remea- 
surement after the knife edges had been used a very considerable 
time, their distance was found to be increased, by wear, four di- 
visions only of the micrometer, or not quite two ten-thousandths 
ofaninch, The length of the seconds pendulum deduced from 
these first experiments, differed from the result of the observa- 
tions about to be detailed, only two ten-thousandths of an inch 
in defect. 1 nevertheless think it useless to insert these first ex- 
periments, as the near approximation of the result cannot but be 
deemed to have been in some degree accidental. 
In repairing the knife edges after the termination of the first 
series of experiments, one of them was broken, and when it was 
replaced by another, the distance between them was increased 
about one-hundredth of an inch ; a circumstance which proved 
rather gratifying than otherwise, as it afforded a pendulum dif- 
fering in length from the former one, and which yet gave nearly 
the same result. 
June 9th, 1817, the knife edges being adjusted parallel to each ~ 
other, and the scale and pendulum having remained together for 
several preceding days, the picces A, a, and B, d, were applied 
to the knife edges in the mamner described in the former part of 
this paper, and the following measurements were taken. 
} 
{ 
Distance from A to a, 329-06 divisions. . 
B to b, 366-97. | 
| 
643-0 957-01 | 
642-0 956-01} 
T'abLye continued, 
° Readings of the Micrometer. | Divisions 
ere: | A tobe | Btob. | Scale. | +39-4 in. | 
June | 27-0 620 | 653-0 ) 95651 | 
9th. | 21-0 | 520 | 642-7 | 954-21 | 
13-0 52-0 6425 | 958-01 | 
12-0 | 48-0 638-5 | 95651 | 
18-0 50-0 | 
18-0 | 50-0 
