THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL 



Vol. X. JVTSTE, 1889. No. 6. 



A// coiniminicatio?is for this Jourtial, 'whether relatmg to bitsi7iess or to editorial 

 matters, aftd all books, pamphlets, exchanges, etc., should be addressed to Ameri- 

 can Monthly Alicroscopical Journal, Box 6jo, Washington, D. C. 



European subscriptiotis may be sent directly to the above address accompa^iied 

 by International Postal Order for $i.ij per atinum, or they may be setit to Messrs. 

 Triibner &= Co., 57 Ludgate Hill, London, or to Mr. W. P. Collins, 757 Great 

 Portland street, London, accompanied by the yearly price of Jive shillings. 



Zeiss's Large Photoniierographie Apparatus.* 



Dr. Zeiss supplies for photomicrogvaphic purposes a special .stand, 

 which is generally similar in form and size to the other large stands of 

 the maker. There is. however, in addition, an unusually large stage, 

 with mechanical movements, rotating by rack and pinion, and having 

 a wide opening for use with a low-power objective, giving a verv large 

 field of view^. The Abbe illuminating apparatus is so arranged that it 

 can be easily removed and replaced by special spectral, polarization, 

 etc., apparatus. The body-tube is also of an unusually large diameter, 

 partlv for avoiding internal reflection, and partlv to render possible the 

 use of the low-power objective. 



The microscope is not attached to the same support as the camera, 

 but both parts are on separate stands, which it is claimed is more con- 

 venient for working. The stand, screwed to a metal support which is 

 provided with three levelling screws, is set up at one end of the plat- 

 form A (see frontispiece), which is adjustable for height. At the other 

 end of the platform is an angle-plate, C, which supports an electric 

 lamp ; while the space between the lamp and the microscope M is oc- 

 cupied bv an optical arrangement consisting of two stout metal rails 

 carrying the illuminating apparatus for use with sunlight ; two vertical 

 screens, E and F, movable by rack and pinion, which can be quickly 

 turned on one side, and again brought back exactly to their old posi- 

 tion ; a plane mirror, G, adjustable in height, with coarse and fine ad- 

 justment in the vertical as well as in the horizontal axis, in order to 

 correct slight irregularities in the course of the heliostat ; and a stand. 

 H,for the reception of glasses for yellow and blue absorption liquids. 

 For the use of the arc-lamp, as shown in frontispiece, there is a water- 

 chamber, T, with plate-glass ends for the absorption of the heat-rays, 

 and a lens, L, for projecting the image of the carbon points on the ground- 



* From Journal of Royal Microscopical Society, April, iSSg, pp 278-283. 

 Copyright, 1889, by C. W. Smiley. 



