Monthly Microscopical"! / QOI \ 



Journal, June 1, 1870. J V ^^^ / 



NOTES AND MEMOKANDA. 



A Graduating Diapliragm. — In a recent number of the * Chemical 

 News ' there appears a letter from Mr. Henry Morton, of the Franklin 

 Institute, Philadelphia, in which he quotes from the Journal of the 

 Institute (February) an account " of a new and very ingenious con- 

 trivance by Mr. J. Zentmayer." The instrument is a graduating 

 diaphragm. It consists of two cylinders or rollers with parallel axes 

 and surfaces in contact, having similar conical grooves on their sur- 

 faces, and fine teeth cut at one end of each, which, gearing together, 

 cause them to rotate in unison. There is, theoretically, an objection 

 to a diaphragm of this construction, from the fact that its opening will 

 not always be in the same plane — that is, the smallest cross-section of 

 the space between the rollers will not always be equidistant from a 

 plane at right angles to the line of sight and passing through the axes 

 of the rollers. With the larger opening, this smallest section will be 

 nearest to, and with the smaller, farther from, such a plane. In prac- 

 tice, however, this difference is so small as to be entirely unimportant, 

 and may even, in some cases, be turned to advantage. There are other 

 forms of gradually adjustable stops which have been employed with 

 more or less success, but few, according to Mr. Morton, involving so 

 many elements of durability and convenience. 



A Kew (?) Combination Objective. — At tho meeting (March 9) 

 of the Microscopical Section of the Boston (U.S.) Natural History 

 Society, Mr. C. Stodder exhibited a new objective of unique construc- 

 tion made by Tolles. With its draw-tube closed it was a 3-inch; 

 when fully drawn out, a 4-inch; it had a working distance of only 

 If inch. He also remarked that Professor Eulenstein had written 

 him that Nobert and himseK had resolved the seventeenth band of 

 Nobert's test-jilate with a ^-inch objective made by Tolles ; they had 

 been unable to do so with any other objective. 



The Schooner-yacht * Noma ' has started on her trip of di'edging 

 on the west coasts of Spain and Portugal. Her o^oier and master, 

 Mr. Marshall Hall, is accompanied by Mr. W. S. Kent, of the British 

 Museum ; and as Mr. Kent is one of the active members of the Koyal 

 Microscopical Society, we may expect good results from his labours. 



Dr. Michael Foster, the eminent Teacher of Microscopic Anatomy 

 in University College, and one of the Secretaries to the Biological 

 Section of the British Association, has been elected Preelector in Phy- 

 siology at Trinity College, Cambridge. 



A New American Natural History and Microscopical Society. 

 — There has just been started in the city of Baltimore a society of 

 fifty members, called the *' Maryland Academy of Sciences." It is in- 

 tended to pay special attention to microscopy. The following list of 

 the officers may be useful to those societies which desire to correspond 

 with the new Academy : — Philip T. Tyson, President ; John G. 



VOL. III. Y 



