THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



AUGUST 1858. 



JX. Oa certain Results of Magnetical Observations. 

 By John Allan Broun. 



To Sir David Brewster. 



Tievaiidrum Observatory, India, 

 My DEAR Sir, December 21, 1857. 



I HAVE just had a sight of your article on Magnetism in the 

 new edition of the Encyclopcedia Britannica (vol. xiv. part 1), 

 and I have observed that you notice my results vvith reference 

 to the lunar influence. Most of the results which were obtained 

 by me are so mixed up with large masses of figures in the volumes 

 of the INIakerstoun Observations^ that I was requested by some 

 scientific friends^ before leaving Europe, to publish a popular 

 resume of them. This I deferred from the desire to confirm and 

 render them more general, if possible, by observations to be made 

 near the magnetic equator. As I have now obtained some results 

 from my observations here, you will perhaps allow me to offer 

 you an account of some of those obtained by me in Scotland, 

 and here near Cape Comorin. 



It is not my wish to occupy your attention with the results I 

 had obtained with reference to the lunar magnetic influence; 

 but I may notice, as an evidence of how little is known of the 

 Makerstoun Observations, the statement by General Sabine, 

 "that Toronto is the first and only station at which the nume- 

 rical values at every lunar hour of the lunar-diurnal variations 

 of the three elements have been published" (Proceedings of the 

 Royal Society, March 5, 1857). 



The numerical values at every lunar hour during each luna- 

 tion in the years 1814 and 1815 for the declination, horizontal 

 force, and vertical force, were given in the Makerstoun Observa- 

 tions published in 1848 and 1850. Also the numerical values 



Phil, Mag.S. 4. Vol. 16. No. 105. Au(/. 1858. G 



