376 



Observations of the Magnetic 



[Mat, 



1837. 



Arc. Ther, 



April 30th. 20° 88.0 



12 45 



8 15 



4 



Another set. 20 88.0 



12 45 



8 15 ■ ■ 



4 15 87.8 



May 3rd. 



20 87.0 



12 45 



8 30 



5 



No. 

 Vib, 



1 



101 

 201 

 301 



1 



101 

 201 

 301 



1 



101 



201 

 301 



3, Private mark X. 

 Mean Time 

 h. m. s. 

 43 49.4 

 48 51.3 

 53 53.1 

 58 54.1 



Interv. 

 s. 



302.2 



301.5 

 301.0 



Mean Int. 

 s. 



301.57 

 cor. for temp. 1.43 



1 



6 



11 

 16 



49.0 

 51.2 

 52.6 

 53.8 



h 



302.2 



300.14 

 301.60 







45 37.7 ' 



50 40.2 



55 42.1 



1 43.6 



301.4 

 301.2 



302.5 



301.9 

 301.5 



cor. for temp. 1.43 



300.17 

 301.97 



cor. for temp. 1.38 



300.59 



No. 



April 26th. 20° 0' 



12 30 



9 



85.2 



April 30th. 20 87.8 



11 45 



7 30 



4 87.3 



1 



101 



201 



1 

 101 

 201 

 301 



3, not marked 



h. m. s 



3 43 



48 



53 27.5 



6.11 

 17.1 f 



25 

 30 

 35 

 40 



17.3 



29 



40.7 



51.8 



:?} 



s. 

 311.0 

 310.4 



312.1 



311.3 

 311.1 



310.70 

 cor. for temp. 1.31 



309.39 

 311.50 



cor. for temp. 1.40 



310.10 

 or we have for the time of performing 100 vibrations at the tem- 

 perature of 60° Fahrenheit at Madras. 



Needle 3, X Needle 3. 



s. 

 300.14 

 .17 

 .59 



s. 

 309.39 

 310.10 



Mean, 300.30 Mean, 309.74 



If h and h' represent the magnetic intensities at any two places, 

 and T and T/the times of performing 100 vibrations at those places, 

 then we have 



h' V T / 



applying this, the horizontal magnetic intensity for Madras (that at 

 London being assumed=l.) becomes 



By Needle No. 3, X 

 Ditto ditto No. 3, 



s. 

 2,1738 

 2,2245 



