for determining the difference of meridians ^ &c. 8 1 



fail to rise, separated it from a direct view of Greenwich, 

 at about 20 miles distance. Either from haze in the at- 

 mosphere, or from the too great distance, nothing was 

 seen that night or the next ; which however caused no unea- 

 siness, as we could depend on our instruments and informa- 

 tion. The next morning Capt. Sabine quitted Hastings, and 

 joined Col. Bonne, at his post, on the morning of the 10th, 

 the day appointed for the commencement of the observations ; 

 meanwhile I was joined by M. Largeteau, who remained 

 with me the v/hole time of their continuance, performing 

 every part of a most scrupulous and exact observer, as the 

 observations herewith communicated will abundantly testify. 

 The observations were continued during 12 nights, 10 

 signals being made at each rocket station every night. The 

 weather throughout the whole of this time was magnificent, 

 and such as is not very likely to occur again for some years ; 

 a circumstance of the last importance in operations of this 

 nature, where lights are to be seen across nearly 50 miles of 

 sea, and also by reason of the verification of the sidereal 

 times at the observatories by transits. One night only a local 

 fog deprived us of the sight of 1 3 out of the 20 signals ; but 

 on the whole, out of 120 made at Wrotham, no less than 

 112 were seen from Fairlight (about 40 miles) and 89 from 

 Greenwich ; while out of the same number made at La 

 Canche, qs were observed at the former post. I am sorry to 

 add, however, that owing to a combination of untoward cir- 

 cumstances, which no foresight or exertion on the part of 

 Capt. Sabine or myself could possibly have led us to calcu- 

 late on, or enabled us to prevent, and which the most zealous 

 endeavours on that of Col. Bonne failed to remedy, no 



MDCCCXXVI. M 



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