439 



A paper by Mr. J. M. Coon was taken as read. It described 

 a new finder for the microscope which can be used on any 

 instrument, and will " find " on any stage, whether mechanical or 

 with sliding bar or spring clips. 



Mr. H. Taverner, F.R.M.S., read a paper on " A Simple 

 Method of taking Stereo-Photo-Micrographs and mounting the 

 Prints without cutting." 



The Hon. Secretary read a paper by Mr. W. P. Dollman, of 

 Adelaide, on "A Simple Method of producing Stereo-Photo- 

 Micrographs." The method employed is similar to that first 

 adopted by Mr. Taverner, but subsequently abandoned by him. 



Mr. J. Rheinberg, F.R.M.S., read a paper "On Stereoscopic 

 Effect and a Suggested Improvement in Binocular Microscopes." 

 A detailed comparison was given of the causes of stereoscopic 

 effect with unaided vision and with the microscope, attention 

 being specially directed to the points where they were similar and 

 where dissimilar. Monocular vision, as well as binocular vision, 

 was discussed in both instances, and it was shown that, under all 

 circumstances, there were most important differences — one fact on 

 which great stress was laid being that, in dealing with microscope 

 images seen stereoscopically, we are dealing with an object of 

 which one layer only is in true focus, and all other layers more 

 or less out of focus. In the construction of microscope objectives, 

 attention has been chiefly concentrated on the formation of a 

 perfect image of one plane of an object at a time ; but for good 

 stereoscopic images it was necessary to consider the relative 

 perfection of other planes at the same time. In adapting the 

 monocular instrument to make it a binocular by using the two 

 halves of the objective to form the two eye-pictures, this seemed 

 to have been overlooked. Bv the use of such semicircular 

 apertures to form a picture, all layers out of true focus were 

 represented by semicircular diffusion discs in the image — a most 

 undesirable shape ; but by altering the effective apertures to 

 circular ones by means of stops placed over the objective, con- 

 siderable improvement in clearness could be effected. 



The paper was accompanied by an exhibition of the various 

 forms of binocular microscopes to which reference was made, 

 including the Greenough binocular with two objectives and the 

 Abbe stereoscopic eye- piece. Objects were shown under the 

 Wenham and Stephenson forms of binoculars, with and without 



Journ.'Q. M. C, Series II,— No. 59. 31 



