and the Birth of Microscopical Petrology. 195 



cause of this was not, as in Darwin's case, ill-health, but a perhaps 

 over- scrupulous devotion to a widowed mother who begrudged the 

 time that might have been lost by frequent visits to London. During 

 his mother's life Sorby was accompanied by her on all his summer 

 expeditions, and, indeed, he seldom, if ever, left Sheffield without her. 



When only 20 years of age Sorby commenced his scientific 

 publications by a paper on Agricultural Chemistry, which was read at 

 the Chemical Society in December, 1846.^ This paper was based on 

 132 determinations of sulphur and phosphorus, made hj himself, in 

 different ci'ops. Very soon, however, his attention was directed to 

 a subject which all through his life had a great fascination for him, 

 namely, the mode of deposition of sedimentary deposits, and the 

 conclusions that may be derived from their study. The gardens of 

 the house at "Woodbourne ran down to the River Don, and here he 

 carried on various experiments on the flow of water and the deposition 

 of sediment. He tells us, too, that one day, while walking out to 

 Orgreave, he was caught in a shower of rain, and whilst sheltering in 

 a quarry near Handsworth his attention was directed to the current- 

 structures exhibited in the sandstone rocks. For these structures he 

 proposed a new classification, and he also prepared a map of the 

 Eother and Don to illustrate the changes in the courses of these 

 rivers.^ (See "Fifty Years of Scientific Research," p. 4.) 



Sorby has told us in very explicit terms how his mind was first drawn 

 to the study of rocks — by means of thin sections for examination under 

 the microscope — at a date long anterior to the publication of the epoch- 

 making paper we have alluded to at the commencement of this article. 

 After stating that at a very early date he was attracted to the study 

 of the shells in the Bridlington Crag, and that he employed the 

 microscope in their study, he says that he had made the acquaintance 

 of William Crawford Williamson, while they were both very young 

 and were journeying together from Scarborough to York. Williamson 

 was an adept in the preparation of sections of hard substances for 

 microscopical study. His maternal grandfather and uncle (the 

 Crawfords) were skilful lapidaries, and young Williamson in his youth 

 learned the use of diamond- and emery-wheels and the general art of 

 the lapidary. (See "Reminiscences of a Yorkshire Naturalist," 1896, 

 pp. 5-6.) Sorby says that he was led to visit Williamson at Manchester 

 some time between 1842 and 1849, and " found him making sections of 

 fossil wood, teeth, scales, and bones. He showed me how to prepare 

 them, and on my return home I made similar sections. It occurred 

 to me, as early as 1849, that a great deal might be learned by applying 

 a similar method to the study of the structure of rocks, and I show 



1 Chem. Soc, Mem. iii (1845-8), pp. 281-284; Phil. Mag., xxx (1847), 

 pp. 330-334. 



^ Sorby's papers on these subjects wiU be found in Sheffield Lit. and Phil. Soc. 

 Eep., 1847, Aug. 6, Dec. 3; 1848, March 3; 1850, p. 13. Proc. W. Torks. 

 Geol. Soc, iii (1851), pp. 220-224 ; (1852), pp. 232-240 ; ibid., vii (1854), 

 pp. 372 et seq. Proc. Yorks. Phil. Soc, i (1855), pp. 372-378. Brit. Assoc Eep. 

 (1855), pt. 2, pp. 97-98; (1856), p. 77. Sheffield Lit. and Phil. Soc Eep. 

 (1858), p. 9. Brit. Assoc Eep. (1858), pt. 2, p. 108. Geologist, vol. ii (1859), 

 pp. 137-147, etc. 



