FOR DETERMINING THE MEAN DENSITY OF THE EARTH. 
345 
Seventh Series. Pendulum 1821 in heat. 
1856. Jan. 8. — Commencing about 2 hours before noon. Mr. Dunkin observed 1821 
from the beginning of 103 to the beginning of 105 ; and Mr. Ellis 
from the end of 105 to the beginning of 107- Mr. Ellis observed 
8 from the beginning of 103 to the beginning of 107. 
Jan. 9. — Mr. Dunkin observed 1821 from the end of 107 to the end of 112. 
Mr. Dunkin observed 8 from the end of 107 to the beginning of 
109 ; Mr. Ellis from the end of 109 to the beginning of 111 ; and 
Mr. Dunkin from the end of 111 to the end of 112, about 1^ hour 
after midnight. This closed the Seventh Series. 
Eighth Series. Pendulum 8 in heat. 
Jan. ] 1. — Mr. Dunkin observed 1821 from the beginning of 113 to the begin- 
ning of 117. Mr. Ellis observed 8 from the beginning of 113 to 
the beginning of 115; Mr. Dunkin from the end of 115 to the 
beginning of 117. 
Jan. 12. — Mr. Ellis observed 1821 from the end of 117 to the end of 118; 
Mr. Dunkin from the beginning of 119 to the beginning of 121 ; 
and Mr. Ellis from the end of 121 to the end of 122. Mr. Ellis 
observed 8 from the end of 117 to the end of 122, about 2 hours 
after midnight. This terminated the Eighth Series, and the whole 
operation. 
Section X . — Comparisons of Clocks, 
69. The clocks were compared by means of a Solar Chronometer, sometimes three 
times and sometimes four times at each interruption of Swings. When there are 
three comparisons, all are made by one observer; when there are four, they are 
usually (but not in every case) made by two observers. The discordance of the 
different comparisons in each group does not exceed 0®'01 or 0®’02. 
The following Table contains the Mean of each group of comparisons, and the 
computation of the Log. Rate of Shelton upon Earnshaw. 
2 z 
mdccclvi. 
