Improvements in the Microscope. 345 



Mr. J. De C. Sowerby, 62, Pratt St. Camden Town, it would 

 enable that gentleman to give a better figure than it will be 

 possible to do from dried ones ; and while I am making this 

 request, I may as well include my friend Curtis, who has sig- 

 nified his desire on the covers of his unrivalled - British En- 

 tomology *' to be favoured with specimens of new and rare 

 plants, free of expense, to be figured in his truly beautiful 

 and splendid work. — J. E. Bowman, {late of Gresford, Den- 

 bighshire). — Elm Place, near Manchester ; 15th May, 1838. 



Improvements in the Microscope. — Perhaps it may not be 

 considered out of place in f The Magazine of Natural Histo- 

 ry? to notice some improvements and simplifications on that 

 most important aid to the naturalist — the microscope, made 

 by myself. . , 



These consist in producing the two crossing motions of the 

 stage, and in regulating the light, in the following most facile 

 modes. My microscope has a square stem, with a rack and 

 pinion, the latter having a milled head, recently added by 

 myself, 2f inches in diameter, in order to obtain readily a to- 

 lerably accurate adjustment of the focus ; but the minute 

 adjustment is effected by a fine screw, with a milled head, 

 recently fitted to it by Mr. Andrew Ross, who has likewise 

 furnished me with a new body, three of his admirable achro- 

 matic compound objectives, and three astronomical eye-pieces; 

 and thus it is as perfect in these respects, as, I believe, any 

 microscope now in existence. It is likewise now indeed very 

 greatly improved by the exceedingly pleasant mode of exar 

 mining objects, effected by the simplification and improve- 

 ment of the stage by myself. The stage was originally mount- 

 ed upon a bracket, proceeding from the upper sliding socket 

 upon the stem, and had a steady-pin in addition to the screw, 

 by which it was fixed to the socket, and expressly designed 

 to prevent any side motion of the stage, as usual. Now, I had 

 only to remove the steady-pin, and thus obtained the sideway 

 movement of the stage in a most simple and effectual manner. 

 This was a very great improvement, and afforded much faci- 

 lity in viewing the different objects ; still, however, the op- 

 posite motion, to or from the observer, was wanted, and this 

 I have also been able to effect in as simple and useful a man- 

 ner, as the motion sideways. Mr. Ross had fitted to my stage 

 his valuable speculum for illuminating opaque objects side- 

 ivays ; and for this purpose had mounted a pipe or socket to 

 receive the stem of the carriage of the speculum, in a small 

 plate of brass, which he fixed by screws to the underside of 

 the stage, on the left side of it. This gave me the opportunity 

 of employing another cylindrical metal stem, to fit his pipe 



g g 2 



