266 The Proposed Pendulum Operations for India. [No. 4; 
south-east of Japan), at Sitka in Russian North America, at Petro- 
paulowski, Valparaiso, St. Helena, and St. Petersburg. He deduced 



































an ellipticity of 54, from his observations. 
Schumacher, the celebrated astronomer of Altona, conducted in 
1829-30 a series of experiments with Bessel’s apparatus, at the castle 
of Guldenstein, in order to determine the Danish standard, which was 
to be a certain fractional part of the length of the seconds’ pendulum, 
at the level of the sea, in latitude 45.° In order to estimate the in- 
fluence of the air, he used, instead of a ball, a hollow cylinder of- 
platinum, made by Repsold, inside which a second solid cylinder, 
also of platinum, fitted perfectly true, The outer cylinder was closed 
by covers of the same diameter screwing on to it, which were both 
perforated; the clamp holding the wire was fastened on to the top, 
and into the bottom was screwed a point with which the contact was 
made in measuring the height of the cylinder by the micrometer 
screw. 
The pendulum was swung under four different circumstances, viz. 
the long pendulum, with and without the inner cylinder, and the short 
pendulum, also with and without it; and as exactly the same surface 
was exposed to the air in each case, the influence of it could be 
computed, which was done by a formula deduced by Bessel. The 
reduction of the observations was made by Professor Peters. One 
novelty was introduced, viz. that of computing out the attraction of 
the ground on which the observations were taken. A square space 
having a side of 600 toises (1279 yards), in the middle of which the 
observatory was situated, was subdivided again into 36 squares of 100 
toises (213 yards) a side; in each of these borings were made, and 
specimens of the earth removed and their specific gravities determined ; _ 
as these were very nearly the same, a mean of the whole was taken. 
The height of the floor of the pendulum room was 343 toises (220.6 
feet) above the mean sea level, and the attraction of this plateau of 
the earth’s crust introduced a change in the length of the second’s 
pendulum of 0.000215 English inches. 
Carlini, whilst measuring the Piedmontese are in 1821-23, took a 
series of pendulum experiments at the Hospice on Mount Cenis, with 
the view of determining the density of the earth. His pendulum was 
formed of a heavy sphere suspended by a wire, which was attached to 
