1865.] The Proposed Pendulum Operations for India. 261 
On the return of Captain Freycinet, the French government sent 
out another expedition under Captain Duperrey. He was supplied 
with two of Captain Freycinet’s brass pendulums, viz. one with a 
eylindrical rod, and the one on Kater’s principal. He observed at six 
stations, viz. Ascension, Mauritius, Port Jackson, Falkland Isles, 
Toulon, and Paris. In deducing the ellipticity, he combined his 
results with those of Freycinet only, and obtained values varying from 
360 10 395: 
During Ross’s voyage to Baffin’s Bay in 1818, some observations 
were taken at Brassa, in the Shetlands, and at Hare Island, with a clock 
fitted with an invariable pendulum vibrating on a knife edge, which 
rested on hollow agate cylinders. Observations were repeated at these 
stations, and a further set taken at Melville Island, on Captain Parry’s 
first voyage to the North Pole in 1819-20. Captain Sabine conducted 
both these experiments, using the same instruments. 
In 1822, the English Government sent out an expedition under 
Captain, now General, Sabine, for the purpose of extending the 
enquiry commenced by Captain Kater; for both Kater and Biot had 
come to the conclusion, from a discussion of the experiments, that 
no decisive result of the earth’s ellipticity could be obtained from 
them, on account of the smallness of the comprised arc, and the 
variations of local density. Captain Sabine visited thirteen stations 
between Bahia, S. Lat. 12° 59’ to Spitzbergen N. Lat. 79° 50’. 
He had with him three pendulums of Kater’s invariable pattern, 
which were all swung at each station, Besides these he had the two 
clocks and attached pendulums which he had already used on his 
arctic voyages. His method of observation was similar to Captain 
Kater’s; all the pendulums were swung in London at Mr. Browne’s 
house, both before and after the expedition. 
The ellipticity deduced from the experiments at Captain Sabine’s - 
stations was =4,-z, from the same combined with Kater’s 51,.;, and 
combined again with Biot’s sis-p, and from’a general combination of 
all of these, 535-7. The observations of the detached pendulums only 
were used in these determinations; for though the clock pendulums gave 
closely coinciding values of ellipticity, still being acted on by other forces 
than gravity, their results are less reliable, and are only valuable in so 
far as they afford an independent corroboration of the other results. 
