SERPENTINE. 205 



of -magnetic investigation, has been accustomed to ob- 

 serve the variable nature and tendency of this force. 

 The experiments of Saussure appear to have been for- 

 gotten; as those of Captain Flinders seem to have been 

 equally neglected. That the amount of this magnetic 

 deviation is often very considerable, but extremely va- 

 rious, I have ascertained on the Western coast of Scot- 

 land ; but it is a subject which, beyond this passing 

 notice, is not within the limit of this work. 



Serpentine is a simple rock, essentially ; though there 

 are varieties, of a compound character, independently 

 of the numerous ostensible ones resulting from the co- 

 lours for which it is so noted. But, for all this, it is 

 best, as usual, to refer to that grammar of geology so 

 often here quoted. There is little opportunity, from 

 this country, to learn what features a territory derives 

 from it, or what are the resulting soils. The cliffs of 

 the Lizard are bold, broken, and picturesque, but the 

 land is without any marked character; and the same is 

 true in Unst and Fetlar. Of the soils of these tracts, 

 it is difficult to give any general character. Yet every 

 where in Shetland, except where limestone and ser- 

 'pentine exist, the rocks are deeply covered with peat; 

 while, if occasionally found on limestone, it never oc- 

 curs on the Serpentine, though the neighbouring tracts 

 of gneiss and the other schistose rocks, are covered 

 with it. Still, that soil is not uniform ; since, while 

 covered with verdure;, in some places, it exhibits, in 

 others, an arid brown desert of earth and loose stones. 

 The climate of Shetland does not permit us to know 

 whether even that soil might not, under better skies, 

 be adapted to cultivation : at the Lizard, the ser- 

 pentine district is favourable to the growth of wheat. 

 It must be added, that in this country, at least, Ser- 

 pentine resists decomposition, no less than dis Integra- 



