Constitution and Structure of the Interior of the Globe. 29 



objections to this are, that the microscopic character of the 

 substance of the film is different from that of peat, being with- 

 out vegetable fibres ; and that the water of the lakes and 

 mountain tarns of Westmoreland are never, that I am aware, 

 discoloured by peat, which, indeed, is not abundant in the 

 lake district, is chiefly confined to the hollows of the higher 

 hills, and, I believe contains very little soluble matter capable 

 of imparting a brown colour to water, supposing that this 

 colour is owing to dissolved mater, and not merely to sus- 

 pended particles of peat. 



Whether a film of soot, or of black matter, such as I have 

 pointed out, has been observed on any other lakes, I am igno- 

 rant ; I am not aware that it has been described before. 

 Were attention, however, paid to the subject, it is probable 

 that the same appearance would be observed elsewhere ; and 

 it may be deserving of attention, not only as a matter of curi- 

 osity, but also as an indication of currents of air, and of the 

 course and spread of effluvia.* 



The Oaks, Ambleside^ 7tli May 1844. 



Outlines of Mr W. HopkirCs JResearches in Physical Geology. 

 1st, 2d, and 3d Series. (London, 1839-1842.) By Charles 

 Maclaren, Esq., F.R.S.E. Communicated by the Author. 



Physical geology, which treats of the structure of the globe 

 in mass, without reference to the succession of rocks at the 

 surface, has been greatly advanced by the labours of this able 

 mathematician. The results to which the present researches 

 have conducted him are new and curious, as well as geolo- 

 gically important. So far as T know, they have not yet found 

 their way into any of the geological works now in circulation ; 

 and for this reason, as well as on account of their intrinsic 

 value, a popular outline of these results may be useful. 



Modern science is rich in wonders. Who would think that 

 the sun and the moon, bodies so distant, and of which in most 



* The black-rains of Canada, also the film of carbonaceous mat- 

 ter observed on the surface of Loch Earn by Mr Milne, as noticed in 

 one of our volumes, appear to have the same origin as that above 

 described. — Edit. 



