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Remarks on the Binoculah Microscope. 

 By F. H. Wenham, Esq. 



I have been frequently asked why I have not termed my 

 binocular the ''Stereoscopic Microscope?" I may reply that 

 the prevailing idea of stereoscopic vision is more connected 

 with the combined effects of two separate objects, or pictures, 

 than the solid appearance of a single body, having bulk or 

 thickness. AVhat I should term a " Stereoscopic Microscope" 

 would be literally two microscopes, with their object-glasses, 

 placed side by side, like an opera glass, with similar adjust- 

 ments for the distance between the eyes. If such an instru- 

 ment were furnished Avith erecting-glasses and draw-tubes, 

 for varying the magnifying power, only one power of object- 

 glass would be requisite, and I have no doubt that in many 

 applications it Avould be found serviceable, as for the detec- 

 tion of forged trade-marks, &c., and irregularities of pattern. 

 Two single lenses, of about 1^-inch focus, afford some 

 curious results. Taking for example such objects as the 

 similar titles of two different advertisements from a news- 

 paper, or the headings from the various pages of a book in 

 large type, the letters will appear in some places to rise up 

 hill, and in others to fall away, or lay all aslant in a most 

 fantastic manner, indicating that the type has not all been 

 cast in the same matrix, and that the spaces are irregular, 

 both in parallelism and thickness. Two postage-stamps also 

 afford good objects. Many will be found so nearly alike 

 that their combined images appear quite flat, but very fre- 

 quently the head appears like a bust, either above or below 

 the matted ground, accordingly as they are transposed either 

 to the right or left, thus showing that there is considerable 

 irregularity either in the plates or the mode of printing. 



The numerous microscopes that have been altered into 

 binoculars in accordance with my last principle, and also the 

 large quantity still in the course of manufacture, will, I think, 

 justify me in making the assertion without presumption, that 

 henceforth no first-class microscope will be considered com- 

 plete unless adapted with the binocular arrangement. Tak- 

 ing this for granted, it will be to the interest of our best 

 makers to get up their object-glasses in future so as to give 

 every possible advantage to the requirements of the principle. 

 There have been some complaints that, with the highest 

 powers, as the ^V^h and ^th, and in some instances (but 

 not always) the itli or ^th, a portion of the field of view is 

 obscured, rendering it almost impossible to use the two 



