MAGNETIC OBSERVATIONS. 



35 



Errors of Pocket Chronometer, Fletcher, No. 906. 



This chronometer (Fletcher, 906) was habitually carried in my pocket. It was 

 accidentally allowed to run down on the night of December 17th and 18th, 1865, 

 and after remaining stopped twelve hours was wound and compared. Some time 

 between 5 h P.M. of April 13th and 3 h P.M. of April 14th, 1866, it stopped for 

 about l m 37% but started again of itself. On June 20th, 1866, when its face showed 

 gh ^gm p ]y[ if. stopped without any apparent cause, and, as it would not run again, 

 it became useless. 



In observing at San Francisco the box chronometer T. S. and J. D. Negus, No. 

 1287 was used. The observations on June 26th, 1866, showed it to be 

 gi, jgm gs 2 f as t of local mean time; 



and 



Q, gm 45^(j f as t of Greenwich mean time. 



