98 Mr, Herschel's account of a series of observations 



July 17th. The loss of observation 1, in columns I. and 

 III. was occasioned by the observers mistaking the mi- 

 nute. It was however very accurately taken by the second 

 observer. 



Comparison of Chronometer and Clock. 



Chronometer. 

 Before 9'* 21°' 

 After II 11 



Clock. 



17' 



3.68* 

 18 52 21.72 



Mean Error and Rate of Sidereal Clock. 

 Mean of 7 ♦ s j Mean error. 



15" 30° 



47-56' 



Mean rate. 

 — 0.06 



Comparison from 16th to 17th — 1.40. 

 Chronometer fast i*" 19.008 



The ninth rocket exploded the moment it began to ascend; the time noted 

 cannot be depended on. 



