DISCUSSION AT SHEFFIELD 223 



dealing with, the work of Sorby that account could with advantage 

 be extended to include not only the work of Sorby, but his life as 

 well. In the case of a man who had done fo much for science and 

 incidentally for civilisation as a whole, we should have a permanent 

 record of this man's birth, training, and career in detail up to his 

 death, apart from the question of his work. 



As regards the microscope as an instrument, he agreed that it 

 was the optician's affair. There were many comments in the papers 

 on the different forms of microscopes. His experience had been that 

 there were many microscopes on the market capable of giving 

 excellent results when properly used, but they were not made to meet 

 the particular fads of individual workers. Results were dependent 

 more on the individual than upon the particular type used. There 

 was in use in his laboratory four different microscopes — one Austrian, 

 one French, one modern, and one ancient British. It was possible 

 to get good results from all of these. The two oldest were the 

 Austrian and the old British. The latter was perfect in almost 

 every respect, whilst the stage of the Austrian could be moved 

 through quite a considerable angle in the direction in which it should 

 be perfectly rigid. He did not think they need fear much from 

 the superiority of the Austiian make of microscope. 



With regard to stages, he uttered a word of warning — do not 

 get a levelling stage. It was a distinct advantage to have an up- 

 and-down movement of the stage in order to avoid altering the 

 light sources for sections of varying thickness. On the question of 

 light there were a number of elaborate schemes for lighting for 

 visual work, but they got excellent results with the ordinary electric 

 bulb with the interposition of a ground glass screen. One could 

 get a light sufficient to show all detail, and it did not tire one's 

 eyes. As to the source of light for photographic work, he was 

 rather interested in some of the papers in which it was suggested 

 that the arc was too uncertain a source and suffered from flickering. 

 They had tried both the arc and the '' Pointolite," but preferred 

 the arc, and got excellent results from it. 



Mr. Atkinson pointed out that the focussing arrangement for 

 long distance work was one that required a great deal of attention. 

 At times a considerable extension of bellows is required to take a 

 photograph, and unless a really good apparatus for focussing was 

 available, it was very difficult to get a fine adjustment. 



With regard to higher magnification, one direction in which he 

 anticipated this would be an advantage was in the disproving of 

 certain theories at present in vogue with regard to crystallisation, 

 but there was still a tremendous field to be explored with the facili- 

 ties which were now available. Another difficulty with regard to 

 Mgher magnifications was the question of polishing and etching. 

 With the present method of polishing it was practically impossible 

 to get a plain surface to examine, and when one came to etoh the 

 difiiculties were increased. The difficulties were really enormous, 

 and until they were removed there would be great difficulty in 

 examining steels, let alone photographing them at high magnifica- 

 tion. 



