2i president's address. 



and in ponds, &c. in our more immediate vicinage, these singularly 

 beautiful organisms appear to be fully represented iu our dis- 

 trict. I may reiaark in particular, the occurrence in great 

 abundance, in the water supplied to the town by the Whittle 

 Dean Water Company, of the frustules of a minute discoid species, 

 probably Cyclotella opeixulata, of Smitli's Synopsis. Of course 

 others, as Cymhellce, Cymatopleura, &c., are found with it, but 

 not nearly so frequently. 



" All well, some future time, I may attempt a more extended 

 review of the species of our neighbourhood. I don't think I have 

 anything new in Phanerogams to report, affecting our Flora." 



I have been furnislied by ]Jr. llichardson with a proof im- 

 pression of some curious illustrations of the microscopic appear- 

 ance of different varieties of coal, which will shortly ai)pear in a 

 work on which he is now engaged. The subject of Microscopic 

 and other investigations of coal, was alluded to in the address of 

 my predecessor in this chair, Sir Walter Calverly Trevelyan, 

 who justly mentions this train of incjuiry as one that, especially 

 in a coal district, might be most properly pursued. In his 

 practical and sensible observations on the difficulty of describing 

 coal by any single and accurate dcjfmition, I entirfily agree. 

 Indeed, such is tlie imperfection of human knowledge — such the 

 vagueness and uncertainty of human observation, that it is 

 almost impossible to apply and combine the results derived 

 therefrom, in the same exact manner that mathematical reason- 

 ing can be applied. Some of the specimens exhibited in the 

 coloured plates of Microscopic sections of coal, in the work 

 alluded to, are from my OAvn collection, having placed them 

 under the careful observation of Dr. Aitken, of Glasgow, by 

 whom the draw ings were prepared ; and I have much pleasure in 

 quoting the following observations from the correspondence with 

 which he favoured me on the subject : — 



" There can be no doubt that all the coaly substances, called 

 coal in common language, are both chemically and microscopi- 

 cally the result of changes (not altogether understood) upon 

 vegetable matter. 



'• As coals are generally known and distinguished by various 



