ELEMENTARY PHOTO-MICROGRAPHY. 13 



district free from the vibration of passing vehicular 

 traffic, monochromatic and electric or limelight, the 

 heliostat for sunlight, expensive apochromatic lenses, 

 or even specially-corrected microscope objectives 

 will not be requisitioned for carrying out any of the 

 instructions hereinafter given, but only such simple 

 apparatus as the ordinary photographer possesses, 

 with the addition of a microscope. Indeed, for low- 

 power work, a camera, a paraffin lamp or lantern, 

 and a few home-made articles are all that are 

 essential, no microscope being required, as the 

 operation is one of simple enlargement. The whole 

 of the processes hereinafter described are intended 

 to be carried out by artificial light. 



There is a difference betwixt the visual and the 

 actinic foci, and objectives corrected for photo 

 graphy are sold, but ordinary objectives made by 

 good firms give results not to be despised. Even 

 with high powers tolerable negatives can be ob- 

 tained, and the brain work of a practical manipula* 

 tor will often compensate for lack of expensive 

 apparatus. 



The use of eyepieces is condemned by some 

 writers without much reason. If the eyepiece be 

 not used a long extension of camera is needed, 

 whereby the apparatus becomes troublesome, and 

 the result is not one jot better than when the eye- 

 piece is employed. The loss of light occasioned 

 by its use is more than compensated for by the 

 compactness of the arrangement, whereby the opera- 

 tor may see or control the whole of his focussing 



