682 



GEODESY AND PENDULUM EXPERIMENTS. 



The number of vibrations made by the clocks in London was 

 ascertained before the departure and after the return of the 

 Expedition. 



London. Mean. 



Clock I. 

 Clock IL 



Jan. 1819 

 Dec. 1820 

 March 1819 

 Dec. 1820 



- 86392- 5673 l^^oQo. 4,., q 



- 86392 -3353 J ^^^^^^^^^ 



■ «^4^^-9^^ } 86496-9855 



- 86496-9741 



The daily acceleration of a pendulum, from the mean of the 

 results with both pendulums, is 74-734 vibrations between the 

 latitudes 51° 3 r 08-4^' and 74° 47' 14-36" N., giving the elllp- 



ticity of the earth oTqT^' 



2. Observations in Spitzbergen by Captain Sabine. 



Similar observations were made by Sabine at Spitzbergen in 

 latitude 79° 50' N., in the year 1823. 



Experiments were also made by Sabine at Hammerfest in 

 latitude 79° 40' N. 



Comparing together these results with those which have been 

 obtained by Sabine at Greenwich and at Paris, we get — 



Length of Seconds 

 Pendulum. 



Measure of the 

 Force of Gravity, 



At Spitzbergen - 

 „ Hammerfest - 

 „ Greenwich - 

 „ Paris 



39-21469 

 39-19475 

 39-13983 

 39-12851 



32-2528 

 32-2363 

 32-1912 

 32-1819 



3. Parry's Experiments at Port Bo wen. (Third Voyage.) 



These experiments on the time of vibration of one of Kater's 

 Pendulums, were made at Port Bowen, in lat. 73° 13' 39-4" N., 

 long. 88° 54' 48-55" W., and compared with experiments with the 

 same pendulum at Greenwich, before the Expedition left England, 

 and also after its return. The number of vibrations made at Green- 

 wich in 24 hours mean time reduced to the level of the sea, and in 

 vacuo at the temperature of 50° Fahr. in April 1824, was 86159 -315, 

 and in November 1825, was 86159-554; the difference 0-24 

 is probably due to the wear of the knife edges, which gives the 

 average 86159*434 at Greenwich, to compare with 86230-242, 

 the mean of two series of observations made at Port Bowen. 

 Taking these values, the elHpticity of the earth is found to be 



— — — -, and the comparison of the force of gravity at the two 

 places is at once determined. The length of the Pendulum being 



