558 PBOCEEDINGS OF THE SOCIETY. 



by Scott Archer, gave a structureless film and a pure stain-like 

 deposit, but this was speedily and completely superseded by the 

 iron development and coarse granular deposit for the sake of the 

 meretricious advantages of redevelopment and local intensification as 

 a correction for error of exposure. 



The question of illumination of microscopic objects has its im- 

 portance too ; in this matter the slides must speak for themselves. 

 It is well known that the same objects may be shown very differently 

 under various degrees and qualities of light. In all cases, in order 

 that a comparison between the enlargements to be shown upon the 

 screen may be made with the aspect under the Microscope itself, the 

 light used for producing the photograph has been the ordinary 

 mineral oil lamp. Indeed, no unusual accessory of any kind has been 

 employed — no monochromatic light or any other expedient, but the 

 object was arranged in the ordinary way, examined and adjusted with 

 the A eye-piece, and the photographic image obtained at once by 

 placing the camera in front of the eye-piece, the only change being 

 the readjustment of focus, according to the degree of enlargement 

 required in the negative. No allowance, or correction, was foimd 

 necessary with the objectives employed to make the visual and actinic 

 foci agree. The objectives were high class, of English make. 



It is hardly necessary to say that the negatives are entirely 

 untouched, excepting to remove mechanical defects inseparable from 

 the mounting of microscopic objects, and that otherwise the resulting 

 slides are the result of pure photography. 



The process employed is that known as the Woodbury-type 

 process." 



[The remainder of the note deals with the Woodbury process, and 

 the " Sciopticon " used. See Mr. Smith's remarks infra.'\ 



Mr. Crisp said that Mr. Evans claimed that he had been more 

 than ordinarily successful in overcoming the chief difficulty in the 

 matter, that of obtaining such a focus as would properly represent 

 the various planes of even deep objects, and this without loss of 

 natural effect. 



The President said that the meeting were very much obliged to 

 Mr. Evans and his colleague for this exhibition, which was certainly 

 the most interesting which he had yet seen. He had been much 

 struck by the beauty of many of the pictures, and inquired if there 

 was anything special in the mode of preparation, which allowed of so 

 much delicate detail being shown without any sacrifice of natural 

 character or beauty of result. 



Mr. Smith said there was nothing special in the mode of produc- 

 tion. The photographs were all taken with an A eye-piece, and by 

 the light of an ordinary paraffin Microscope lamp. The slides were 

 prepared by what was known as the Woodbury process — that is they 

 were printed from metal plates — the result being that they got very 

 much greater transparency and better detail, with a uniform colour. 

 When once the proper tone had been obtained any number of prints 

 could afterwards be produced of exactly the same depth. The 

 process was undoubtedly the finest possible for the purpose. 



