ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 



557 



The plate-holder (single) is square, opening at the back to admit 

 the plates, which can be placed either vertically or horizontally. The 

 usual size of plate employed is 4^ by 5^ inches, but there is a " kit " 

 furnished also, which permits the use of plates 3i by 41 — the proper 

 size for lantern positives — which can be very readily made by contact 

 printing from the finished negatives. 



Any coal oil or petroleum lamp of good illuminating power, and 

 which can be placed at any desired height above the table, may be 

 used. The Fiddian Illuminator (originally intended for microscopic 



Fig. 96 



purposes) has been found admirably adapted to use with the camera, 

 and is the one figured in the illustration. It gives a strong white 

 light through the lens composing its front, all the other rays being 

 cut off by the metallic chamber and chimney containing the flame. It 

 can be raised to any required height, and is recommended as being the 

 best lamp for the purpose. 



Although any microscope-stand with axial inclination may be used, 

 Mr. Walmsley finds that those of the size and general form of Beck's 

 National and " Ideal " stands are the best adapted to this class of 

 work. The shortness of tube of tbe " Ideal " renders it specially 

 valuable, whilst the revolving stage adds greatly to the proper 

 adjustment of the object in the centre of the focussing screen, and the 

 substage carrying an achromatic condenser is almost indispensable. 

 A mechanical stage will also be found to greatly facilitate the 

 necessary manipulations, though the very simplest form of stage, 

 with clips, will, with a little care and patience, answer every 

 requirement. 



In using this apparatus, the base-board is to be placed upon a 



