250 PROCEEDINGS OF THE SOCIETY. 



Messrs. Ross. Descriptive reports on this objective by Messrs. Ross 

 and by Mr. Nelson were read to the meeting. 



Mr. A. D. Michael said he perfectly well recollected this lens being; 

 brought out, and Mr. Wenham specially selected one for him and seemed 

 to be very proud of it at the time. He had sent it to Mr. Nelson for 

 examination, but neither he nor Mr. Nelson considered it a very great 

 success, and though he still had it he scarcely ever made use of it. 



Mr. Walter Rosenhain then described at considerable length a new 

 form of Metallurgical Microscope which, together with various pieces of 

 accessory apparatus, was exhibited to the meeting, a lantern picture of 

 the instrument being shown upon the screen in further illustration. 



Mr. Jenkins said that there were several points in which an ordinary 

 Microscope proved inconvenient in the work of examining metal 

 sections, and, so far as he could see, these drawbacks had been succes- 

 fully overcome in the instrument which Mr. Rosenhain had designed 

 with so much care and skill. He thought that the greater steadiness 

 of the fixed tube would be a great advantage, especially for photography. 

 The qualities of the new Microscope, however, could only be truly 

 appreciated by experience, and he should very much like to have an 

 opportunity of trying the instrument himself in comparison with that he 

 now used. He thought, however, that it would be well to say that if 

 anyone purposed taking up the study of micro-metallurgy, he need not 

 be deterred from doing so by the idea that it was necessary to have any 

 elaborate instruments for the purpose, since very good results could be 

 obtained by a simple means. What they wanted most in micro- 

 metallurgy were objectives which would give them a flat field ; but he 

 understood that opticians objected to make these, since the properties 

 which gave flatness of field were, he was told, incompatible with certain 

 other optical properties expected in present-day lenses for general use. 

 The optical firms feared that if they made objectives which would satisfy 

 metallurgists as to flatness of field, their reputation would suffer with 

 those whose work was of a more general nature ; but he thought that if 

 they engraved round the objective some such word as " Metallurgical " 

 this would sufficiently explain that it was designed for a special purpose, 

 and their reputation would then be unaffected. 



With respect to the optical bench, which was exhibited in conjunc- 

 tion with the Microscope, this was no doubt a very good arrangement, 

 but was it necessary for any ordinary work ? In his work he used a 

 Nernst lamp, a simple condenser, and a Beck's cover-glass type of ver- 

 tical illuminator, and he found no difficulty in getting thoroughly 

 satisfactory photographs up to 1000 diameters. 



Dr. Carpenter thought they were very much indebted to Mr. 

 Rosenhain for bringing this instrument before them, and that they 

 ought to recognise that he had attempted, what had not been attempted 

 before, to make an instrument which was perfectly adapted for all 

 requirements of this class of work, which was increasing in importance 

 every year. If the advantages which were claimed for this Microscope 

 were borne out by experience, Mr. Rosenhain had certainly placed 



