272 PROGRESS OF SCIENCE IN THE CENTURY. 



of making sections was published in 1831.* But 

 these early hints had little result, and it seems fairly 

 certain that the first to use and appreciate the method 

 of studying thin rock-sections in transmitted line 

 under the microscope was Dr. H. Clifton Sorby of 

 Sheffield (1850), who had been stimulated by the 

 sight of a collection of !N"icol's preparations which 

 had been preserved and added to by Alexander Bry- 

 eon, an optician in Edinburgh. 



Professor Zittel notes that, in 1852, Oschatz ex- 

 hibited in Berlin a series of microscopic sections of 

 rocks which he had made, but his results seem to 

 have been regarded as little more than curiosities. 

 A proof of the value of the method was needed, and 

 that was furnished in 1858 by Sorby in a classic 

 memoir " On the microscopic study of crystals, indi- 

 cating the origin of minerals and rocks." f The 

 next steps, and for many years almost all the im- 

 portant steps, were taken by continental geologists. 

 " Even Sorby's papers, which continued to be most 

 suggestive in this line of work, had reference only 

 to very special points ; and it may be doubted if his 

 greatest service was not the transplanting of his ideas 

 and methods to Germany, where they were destined 

 to rapidly take root, and bear a fruitful harvest.":}: 



It was a most fortunate thing for science that 

 Zirkel, as a young student, made Sorby's acquaint- 

 ance in Bonn in 1862, and after many walks and 

 talks became an enthusiastic disciple, soon far to 



* Henry Witham. Observations on Fossil Vegetables, 

 Edinburgh, 1831. See The Microscope, by Carpenter and 

 Dallinger, London (1891), p. 990. 



f Quart. Journ. Geol. Soc. XIV. (1858), pp. 453-500. 



$ G. H. "Williams. Modern Petrography, an account of the 

 application of the microscope to the study of geology. 

 Boston, 1886. 



