H. (KOUCH ON MICROSCOrY IN THE UNITED STATES. 229 



adopted a mirror stem, hinged, so as to give a lateral movement to 

 the entire fittings of the mirror, thus providing an extremely con- 

 venient method of obtaining an exceedingly oblique illuminating 

 pencil. 



Mr. Zentmayer and Mr. Gundlach also exhibited a substage 

 arrangement, which was mounted in such a manner as to give a 

 lateral movement to the entire substage and mirror, the advantage 

 claimed being, that as the axis upon which it swings is so placed as 

 to be as nearly as possible level with the upper surface of the slide 

 upon which the object under examination is mounted, better results 

 are obtained where an oblique illumination is required with an 

 achromatic condenser. Messrs. Ross and Mr. Zentmayer both ex- 

 hibited portable microscopes of extremely ingenious construction, 

 but needing diagrams to render them intelligible. I may, perhaps, 

 here be permitted to state that my own centering adjustments, with 

 which my best stands ave now provided, were claimed by two 

 American manufacturers, but in both cases the claim was proved to 

 be without foundation. 



The accessory apparatus exhibited being of the usual character, 

 and presenting nothing calling for especial remark, it is not neces- 

 sary for me to occupy your time by giving any detailed account of it. 

 I had, however, the pleasure of receiving many valuable hints 

 respecting the improvement and modification of some of the 

 accessories from Dr. Woodward of Washington, Dr. J. G. Hunt 

 and Mr. Holman of Philadelphia, Dr. Ward of Troy, and other 

 microscopists, which, when I have had an opportunity of carrying 

 out, I hope to submit to your further notice. 



With respect to the objectives exhibited, I cannot but feel that I 

 am here approaching a rather delicate topic, as, if manufacturers of 

 microscopes are a little weak upon any subject, it is upon the point 

 of the immense superiority of objectives of their own production 

 over those supplied by their competitors ; and I am sure, therefore, 

 that you will agree with me in referring those requiring further in- 

 formation to the published reports of the judges. 



Mr. Walmsley, of the firm of J. W. Queen and Cb. ; Dr. 

 Beattie, of Baltimore, and Mr. Edmund Wheeler, of London, were, 

 I believe, the only exhibitors of prepared specimens for the micro- 

 scope. The latter gentleman exhibited an excellent series, including 

 some very fine transparent injections. Mr. Walmsley and Dr. 

 Beattie both submitted some very excellent specimens of the doul.de 



