98 



OBSERVATIONS OF THE MAGNETIC INTENSITY 



to be 65° 48 '.5. Adopting 2 '.8 as the annual decrease of the dip at Geneva, the 

 observations of Professor Forbes would give,, for the epoch 1837, 64° 51 '.0, and 

 those of M. Arago, 65° 14'.9. 



BRIENTZ AND THE FAULHORN. 



These observations were made at places only about fourteen miles apart, but 

 differing in elevation 6800 feet : the lower station itself (Brientz) is about 8900 

 feet above the level of the sea. The Faulhorn was one of the stations of Pro- 

 fessor Forbes in his Alpine observations; and Brientz is about twelve miles 

 W. N. W. of another of his stations, Meyringen. 



The observations at Brientz were made in a field in rear of, and about a hun- 

 dred yards from the White Cross Hotel; those at the Faulhorn nearly on the 

 very summit, and as far from the chalet as the ground would permit. 



The chronometer was rated at Zurich, and the rate, which differed but 

 little from that found at Geneva, has been applied in the following table. The 

 numbers already referred to for Paris, in 1837, have been used in the calcu- 

 lations. 



Ohsei'vations at Biientz and the Faulhorn. 



For Horizontal Intensity. 



Place. 



Needle. 



Date. 



Temp. 



.2 

 d 



xn 



C 



t« O 



:-i 



m 



o 



Time of 



Ten 



OsciU'ns. 



at C0°. 



Sees. 



Coeffic't 



of 

 Corr'n 



for 

 Loss of 

 Magn'm. 



Horizontal 

 Intensity. 



Year. 



Month. 



D. 



H. 



Fah. " 



Paris 1. 



Brientz 



Cylinder 

 Bar 



1837 



Sept. 



22 



11, A.M. 

 121, P.M. 



65.0 

 64.8 



2 

 2 



700 

 600 



33.162 

 36.141 



1.0056 

 1.0020 



Mean, 



1.075 



1.082 



1.078 



The Faulhorn 



Cylinder 

 Bar 



1837 



Sept. 



(6 



20 



3 P. M. 



4 



50.5 

 43.7 



2 

 2 



700 

 600 



33.078 



36.082 



1.0054 

 1.0017 



Mean, 



1.080 

 1.085 



1.082 



For Dip. 



Brientz, 1837, Sept. 22, Needle No. 1, 64° 59'. 5 



No. 2, 65 15 .0 M 



ean, 65° 06'.7. 





The Faulhorn, 1837, Sept. 20, Needle No. 1, 65° 01'. 5 



No. 2, " 01 .9 



Mean, 65° 01'.7. 





Total Intensity at Brientz, compared with Pari 

 " " Summit of the Faulhorn, " 



s as unity, 0.9869. 

 " 0.9874. 





