86 



OBSERVATIONS OF THE MAGNETIC INTENSITY 



Horizontal and Total Intensities and Dip at London and Paris. 



Date. 



Needle. 



Horizontal 

 Intensity. 



Total Intensity. 



Magnetic Dip. 



Paris. 



London. 



Paris. 



London. 



Paris. 



London. 



1837. 

 June, July, Aug. 



Cylinder. 



Bar. 



H. R. 



XT tj 



Lloyd' No. 1. 

 " " 2. 



1.069 

 1.066 

 1.066 

 1.062 

 1.067 

 1.063 



1.000 



0.982 

 0.980 

 0.980 

 0.976 

 0.980 

 0.976 



1.000 



67° 21 '.4* 



69° 17'.8t 



1838. 

 July, Aug. 



Cylinder. 

 Bar. 

 Lloyd No. 1. 

 " " 2, 



Mean, i 



1.066 

 1.008 

 1.007 

 1.066 



1.000 

 0.938 



0.980 

 0.981 

 0.981 

 0.980 



1.000 

 1.021 



67° 10'.5 



69° 12'.3 



1.066 

 1.000 



0.979 

 1.000 



BRUSSELS. 



The horizontal intensity at Brussels compared with that at Paris being well 

 known through the observations of M. Quetelet and others, it is important to 

 me as a verification of my results, and as connecting stations in the United 

 States with those in Europe, to compare my determinations with those already 

 on record. The dip at Brussels is also, no doubt, accurately known from the 

 regular observations of M. Quetelet since 1827; and I regretted that an acci- 

 dent which had happened to my dipping circle at Paris prevented me from 

 farther putting itS: accuracy to the test. The observations for horizontal in- 

 tensity were made in the garden of the Observatory. The chronometer was 

 compared with the observatory clock before and after the observations. 



* The mean of this result and that obtained in 1838, reduced to August 16th, 1837, allowing a 

 diminution of dip yearly of 2'. 8, is 67° 20'.8. 



t The mean of this result and that in 1838, reduced to June 16th, allowing an annual decrease 

 of dip of 2'. 4, (see Major Sabine's Report on the Magnetic Survey of the British Islands,) is 

 69° 16'.0. 



