94 



OBSERVATIONS OF THE MAGNETIC INTENSITY 



Nor does this depend upon some peculiarity in the observations at Paris, 

 since, referring to the observations at London, and taking the horizontal in- 

 tensity there as unity, nearly the same difference appears. 



The horizontal intensities determined by M. Quetelet at these two stations 

 both exceed my results, his number for Florence being 1.1830, and for Milan 

 1.1335. The total intensities obtained by MM. Humboldt and Gay Lussac 

 were, for Florence, 0.9481, and for Milan 0.9733, both of which numbers are 

 less than mine.* 



TURIN AND CHAMBERI. 



The place of observation at Turin was in the Botanic Garden; at Cham- 

 beri, in the park of the Count de Boignes, a short distance only from the 

 town. At Turin the chronometer was compared with the observatory clock, 

 and the same rate was applied at Chamberi. The comparison is made with 

 the observations at Paris in 1838. 



Olservations at Turin and Chamberi. 



For Horizontal Intensity. 



Place. 



Needle. 



Date. 



Temp. 



CJ 



m 

 o 



6 



m 



C 



^ O 



xn 



o 



Time of 



Ten 



OsciU'ns. 



at 60°. 



Sees. 



CoefKcl 



of 

 Corr'n 



for 

 Loss of 

 Magn'm. 



Horizontal 

 Intensity. 



Year. 



Month. 



d. 



H. 



Fah. " 



Paris 1. 



Turin 



Cylinder 

 Bar 



1838 



June 



17 



11, A.M. 



12, M. 



82.5 

 83.0 



2 



2 



600 



33.440 

 36.149 



.9987 

 .9992 



Mean, 



1.096 

 1.093 



1.0945 



Cliainben 



Cylinder 

 Bar 



1838 



June 



(6 



21 



121 P. M. 

 2 



78.2 

 77.5 



2 



2 



700 



33.539 

 36.235 



.9989 

 .9993 



Mean, 



1.090 

 1.088 



1.089 



For Dip. 



Turin, 1838, June 17, Needle No. 1, 63° 48'.8 



18, " No. 2, " 55 .6 Mea 



n, 63° 52'.2. 





Chamberi, 1838, June 21, Needle No. 1, 64° 31 '.5 



No. 2, " 37 .5 M 



ean, 64° 35'.0. 





Total Intensity at Turin, compared with Paris 

 " " Chamberi, " 



as unity, 0.959. 

 0.979. 





* The authorities for these numbers are the same as previously quoted. In the remainder of the 

 paper, unless the contrary is stated, the numbers are derived from the same sources, namely, the 

 Annual of the Brussels Observatory for 1834, or the Transactions of the Brussels Academy of Sci- 

 ences, vol. vi., and the Report of Major Sabine on the Magnetic Intensity. 



