OF MICROSCOPIC OBJECTS. 20$ 



photography of magnified objects has evidently no place 

 here. 



Few slides caused so much astonishment as these minute 

 photographs when first exhibited ; small spots were seen to 

 contain large pictures, and a page of printed matter wa& 

 compressed into the one-hundredth part of a square inch. 

 It would be impossible in this place to give the inquirer 

 any instruction in the manipulation of photography, so it 

 must be assumed that he already knows this. 



We will first consider the process performed by artificial 

 light. The collodion employed in photographing generally 

 shows as much structure when magnified as is found in 

 linen of moderate texture; but this is not always the case,, 

 as some samples bear much enlargement without any of 

 this appearance. It is evident that a structure so coarse 

 would make it entirely unfit for these minute pictures, as 

 all the small markings would be destroyed, or so interfered 

 with, that no great enlargement would be practicable. To 

 obtain almost structureless collodion is not an easy matter, 

 and a clever practitioner in this branch of photography 

 states that he knows of no method to accomplish this with 

 certainty, but he himself tries different samples until he 

 falls upon a suitable one, which he then lays aside for this- 

 object. A beneficial effect is often derived from keeping the 

 collodion awhile, but this is not always the case. The slides 

 should be chosen of an equal thickness, so that when 

 focussed upon one, no re-adjustment may be necessary for 

 the others. The glass should, of course, be free from any 

 roughness, scratches, or other imperfections, and of very- 

 good quality and colour. 



The microscope must be placed in a horizontal position, 

 and the eye-piece removed, the stage having a small clip 

 upon it to keep the prepared plate in position. The nega- 

 tive must be supported at a distance from that end of the 

 microscope tube from which the eye-piece was withdrawn. 

 ^This distance will, of course, vary according to the relative 

 sizes of the negative and desired picture. With an inch 



