126 7. C. Mendenhall—Acceleration of Gravity at Tokio, Japan. 
one meter long it was necessary to “triplicate” it in order to 
compare it oink ig bar. The latter is provided with reading 
microscopes, and by repeating the sat cdeaes two t 
times the result given below was obtained and it is believed to 
be not more than a few hundredths of a millimeter from the 
truth. The results of six determinations of the time of vibra- 
ye one of the knife edges, and the second upon the 
ckher: he values of “g” “corresponding to these are also 
given. 
Length of pendulum ast 100069 meters. 
‘5 (vibrating temp.) 1700090 
0 of vibration, corrected for arc and chronometer. 
1 ais 1 00412 
1°00412 1:00417 
1°00410 1°00417 
Values ‘ g.” 
9°7980 9°7976 
9°7976 9°7966 © 
9°7980 9°7966 
These give a mean value of 9 
as anything more than a first approximation, and, wesc = 
cause I am by no means certain as to just what it ought to be. 
There is no doubt but the correction must be different in the 
two cases of suspension, when the heavy ball of the pendulum 
is above the knife edge and when it is below, as was experi- 
mentally demonstrated by Sabine Altes years ago. I believe 
Sabine also investigated the actual correction to be applied to 
Kater’s pendulum, but owing to the very limited library facili- 
ties afforded residents of this country I am unable to refer to 
his results. When corrected, the above mean will undoubtedly 
somewhat exceed the true value, but no great d of accu- 
racy was attempted either in the adjustment of the pendulum 
or In the measurement of its lengt 
A “Borda’s Pendulum,” made by Salleron, was received 
pity after the conclusion of the above experiments, and as it 
as accompanied by a standard measuring apparatus it was 
: determined to undertake a more accurate and a more extended 
series of observations for the determination of the value of “g.” 
The pendulum was of the well known form used by Borda 
and by many others since his tima The ball was of brass, 
