vi Inventions of William Nicol 277 



then ground down, until the piece of stone was reduced to 

 a thin pellicle adhering to the glass, and the requisite 

 degree of transparency was obtained. Nicol himself pre- 

 pared a large number of slices of fossil and recent woods. 

 Many of these were described by Henry Witham in his 

 Observations on Fossil Vegetables (1831), to which Nicol 

 supplied the first published account of his process. 



Here then geologists were provided with a method of 

 investigating the minutest structures of rocks and minerals. 

 It was now possible to subject any part of the earth's crust 

 to investigation with the microscope. It might have been 

 thought that those who devoted themselves to the study of 

 that crust, especially those who were more particularly 

 interested in the structure, composition and history of 

 rocks, would have hastened to avail themselves of the new 

 facilities for research thus offered to them. 



It must be confessed, I am afraid, that geologists are 

 about as difficult to move as their own erratic blocks. 

 They took no notice of the possibilities put in their way 

 by William Mcol. And so for a quarter of a century the 

 matter went to sleep. When Nicol died, his instruments 

 and preparations passed into the hands of the late Mr. 

 Alexander Bryson of Edinburgh who, having considerable 

 dexterity as a manipulator, and being much interested in 

 the process, made many additions to the collections which 

 he had acquired. In particular, he made numerous thin 

 slices of minerals and rocks for the purpose of exhibiting 

 the cavities containing fluid, which had been described 

 long before by Brewster 1 and by Nicol. 2 In my boy- 



1 Trans. Roy. Soc. Edin. vol. x. (1824), p. 1. 



2 Edin. New. Phil. Jour. vol. v. (1828), p. 94. 



