SIR ROBERT HADFIELD, BART. 115 



one which was read before the National Science Section of that 

 Society, but no copy was kept of it. When residing chiefly in 

 Sheffield I was a Member of this Section, often meeting Dr. Sorby 

 there. It is now no longer in existence. 



Later on Sorby communicated his results at the Bath Meeting of 

 the British Association (" On Microscopical Photographs of Various 

 kinds of Iron and Steel," B.A. Report, 1864, Pt. II, page 189). In this 

 Paper the Author briefly explained how sections of Iron and Steel 

 might be prepared for the Microscope so as to exhibit their structure 

 to a perfection that left little to be desired. He also exhibited 

 a series of photographs taken by Mr. Charles Hoole illustrating 

 the various stages in the manufacture of Iron and Steel and describing 

 the structures which they presented. They showed various mixtures 

 of Iron, of two or three well-defined compounds of Iron and Carbon, 

 of Graphite, and of Slag ; and these, being present in different propor- 

 tions and arranged in various manners, gave rise to a large number 

 of varieties of Iron and Steel differing by well-marked and very striking 

 peculiarities of structure. 



For 22 years the observations attracted little or no attention and 

 when in 1877 Professor Martens, Berlin, and later M. Osmond and M. 

 Le Chatelier, Paris, began to study metals with the Microscope they 

 had to develop independently and anew the craft which Sorby had 

 invented many years before. Sorby lectured on " The Microscopical 

 Structure of Iron and Steel " at Firth College, Sheffield, in October, 

 1882, and stated that in view of the knowledge of fresh facts he had 

 re-examined the whole of his specimens with improved Apparatus. 

 In 1885 by the use of Lenses of high resolving power and large 

 magnification he first discovered the true composite nature of the 

 " Pearly Constituent " of steel as an aggregate of parallel plates, 

 which discovery may be reckoned the crowning achievement of his 

 microscopical research. Sorby announced this discovery to the Iron 

 and Steel Institute in 1886, " On the Application of Very High Powers 

 to the Study of Microscopical Structure of Steel," Journal of the Iron 

 and Steel Institute, Vol. I, 1886, pages 140 to 144. Subsequently 

 he presented to the same Institution his great Paper " The Micro- 

 scopical Structure of Iron and Steel," giving a full account of his 

 methods and the results he had obtained. (Journal I.S.I. , Vol. I, 

 1887, pages 255 to 288). These Papers proved to be the signal for 

 great activity in the field which he had so brilliantly started to explore, 

 but it was really far back in the 'sixties that Sorby originated 

 the Science of Metallography. His work at this period gave cause 

 for an American writer in 1900 to say of him (in the " Metallographist" 

 of April, 1900, Boston, U.S.A.): " Whatever has been accomplished 

 since in microscopic metallography has been done by following in his 

 footsteps. To Dr. Sorby and to him alone is due the pioneer's honour." 



Researches on Rock Sections. — At the period (1849) when Sorby 

 began his researches on rocks, the only available knowledge 

 of the constitution of igneous rocks was that gained either 

 by the field-worker with his hammer or by the indoor Geologist 

 by the tedious processes of chemical analysis. Slices of rock 



