1891.] MICROSCOPICAL JOURNAL. 195 



to secure the best results, and applying these methods as a means of 

 minutely and accurately comparing the powers and performances of 

 different objectives, and of making of such performances records whose 

 accuracy could not be questioned and which could readily be compared 

 with each other. 



When Dr. Woodward was doing the greater part of his testing work 

 homogeneous immersion objectives were unknown, and with high 

 powers the proper adjustment of the cover correction was a matter of 

 thfe greatest importance to secure the best results, and was also often a 

 matter of very considerable difficulty. Dr. Woodward's skill and pa- 

 tience in making these adjustments and in the regulation of the illumi- 

 nation were unrivalled. He often spent half an hour and more in secur- 

 ing a single cover correction, and the makers of microscopic objectives, 

 both in this country and abroad, came to recognize the fact that he was 

 not only absolutely impartial in his tests, but would get from each lens 

 the very best work of which it was capable. The result was that the}- 

 were glad to send him lenses for trial and to obtain his suggestions as 

 to the possible means of improvement, which in this way was strongly 

 stimulated. Since his death microscopic and photo-micrographic work 

 have been carried on steadily in the Museum, but on somewhat different 

 lines, consisting mainly in the practical application of these methods to 

 pathological research and to bacteriology. We shall be very glad to 

 have you spend as much time at the Museum as you can spare and to 

 show you what we are doing there. In this connection I wish to invite 

 your attention to two cases at the south end of the main Museum hall 

 which contain a number of microscopes illustrating the development of 

 and changes in this instrument and its accessories from the time of the 

 first-known compound microscope of Janneus in 1685 down to the 

 present time. In bringing together this collection during the last ten 

 years I have been greatly aided by Mr. John Mayall, of London, who 

 has had so much to do with the formation of the magnificent collection 

 of JNIr. Crisp. Permit me to remind you that, as citizens and sovereigns 

 of the Republic, the Medical Museum belongs to you, and that as Amer- 

 ican microscopists its collection of microscopes and of microscopic slides 

 and material should be a matter for your special interest and care. The 

 collection is very far from being complete — it is only the beginning of 

 what I hope will one day be gathered and carefully preserved in it, 

 namely, a specimen of every different form of microscope, and espe- 

 cially of the earlier forms of American makers, of which we have none, 

 and also specimens of the best work of American microscopists which 

 can be shown by permanent preparations ; and to secure this I ask your 

 assistance. The library of the Surgeon-General's Office, connected 

 with the Museum, is rich in books and journals relating to the micro- 

 scope and its uses, especially in its applications to biology and the med- 

 ical sciences, and is available to all who wish to use it. If you are not 

 familiar with its resources and its index I hope you will become so while 

 you are here. 



I speak first and chiefly of the Army Medical Museum and Library 

 simply because it is the division of the Government with which I happen 

 to be most familiar, but you will find microscopical work going on in the 

 Department of Agriculture, in the National Museum, and elsewhere, 

 and in all these places you will be welcome visitors. 



