now measuring on the Confment. 203 



ing, however, with Mr. Herschel, the impropriety of rejecting 

 all those observations which did not admit of being so com- 

 bined, Colonel Bonne has investigated the general result which 

 the whole body of evidence will afford : the method that he has 

 pursued for this purj)Ose is not explained, but we may suppose 

 that it is analogous at least to that of Mr. Herschel, because he 

 states that all the intervals between the signals shewn by the 

 «<3hronometers were reduced to sidereal time, and corrected for 

 the several rates. The result thus obtained, and which we must 

 presume to be much preferable to the former, is 21' 35",55. 



The clocks at Strasbourg and Paris having been compared 

 with astronomical time, by means of different stars, the ques- 

 tion of their right ascension becomes involved, and the differ- 

 ences in that respect that exist in the catalogues of Maskelyne, 

 Bessel, and Pond. The amplitude of 21' 35",55, which is 

 given by the mean of the three catalogues, when separately 

 computed by each, is as follows : 



Maskelyne . . 21' 35",55 ^ 



Bessel . . . 21 35 ,62 I 21' 35^55. 



Pond .... 21 35 ,49 J 



For these differences there is of course no other remedy than 

 to take the mean ; but it would be a preferable course, on 

 future occasions, to avoid them, by concerting to employ the 

 same stars. 



The amplitude 21' 35",55, combined with the value of the 

 arc in metres deduced from the triangles, gives the mean value 

 of a degree of the parallel, which, combined with the mean 

 ^iegree of the meridian between Greenwich and Formentera, 

 corresponds tO an ellipticity of — - . 



The celestial amplitude between Paris and Brest, having 

 only been determined in the course of the last summer, is not 

 yet reported. 



We have had great satisfaction in learning that a communi- 

 -nication very recently made by the French government to 

 Russia, proposing the further extension of the arc from Czer- 

 nowitz, through the Russian dominions, where the parallel 

 passes north of the Caspian, has been favourably received ; 

 ftnd that an examination of the country, preparatory to its 

 being undertaken, is arranging for the ensuing summer, to be 



