4 LIGHT SCIENCE FOR LEISURE HOURS. 



Somerville first became known to the world. A subject 

 of research, exceedingly difficult and only to be pursued 

 successfully under very favourable conditions, was 

 undertaken by her during the life of her first husband, 

 Captain Grreig, son of High-Admiral Greig of the Eus- 

 sian Navy. She sought to determine by experiment 

 the magnetising influence of the violet rays of the 

 solar spectrum. ' It is not surprising,' says Sir John 

 Herschel on this subject, ' that the feeble though 

 unequivocal indications of magnetism which she 

 undoubtedly obtained should have been regarded by 

 many as insufficient to decide the question at issue.' 

 Nevertheless it was justly regarded as a noteworthy 

 achievement that, in a climate so unsuitable as ours, 

 any success should have been attained in a research of 

 such extreme difficulty. That she achieved, and, what 

 is more, deserved success, will be inferred from the 

 words in which Sir John Herschel indicates his own 

 opinion of the value of her results : ' To us,' he says, 

 6 their evidence appears entitled to considerable weight ; 

 but it is more to our immediate purpose to notice the 

 simple and rational manner in which her experiments 

 were conducted, the absence of needless complication 

 and refinement in their plan, and of unnecessary or 

 costly apparatus in their execution, and the perfect 

 freedom from all pretension or affected embarrassment 

 in their statement.' 



In 1832 Mrs. Somerville published the work on 

 which, in our opinion, her fame in future years will be 

 held mainly to depend. The Mechanism of the Heavens 



