50 The Microscope. 



a strong thumb-nut to clamp the arm rigidly in place. By this 

 construction the body tube may be moved about over every part 

 of a surface six inches square, and may be clamped in place over 

 any part of that surface by means of the thumb-nut at the top 

 of the pillar. The papers to be examined can be arranged on 

 the large stage and secured in place by wire clips. In case it is 

 desired to use the instrument as a class microscope, the arm is 

 clamped fast, the handle screwed on and the pillar unscrewed 

 from the base plate, when the instrument can be handed about 

 as readily as a common stereoscope, and weighing but little more. 



If provision is required for the use of transmitted light, which 

 is but seldom needed, an opening in the stage is provided, and a 

 mirror on the base like that of a dissecting microscope. An arm 

 for carrying a lamp may also be attached to the pillar by means 

 of a clamping collar like that of the stage-arm, when the instru- 

 ment is to be used as a class microscope at night. 



It has not been found requisite to provide for inclining the 

 instrument in use, but if desired it can readily be accomplished 

 by providing a slotted segment on the plate into which the pillar 

 screws, hinging this plate to an under plate secured to the base- 

 board, with a clamp screw to clamp the segment against a projec- 

 tion on the fixed plate. 



The instrument, as made for me by the Bausch and Lomb 

 Optical Co., has proved very satisfactory in use, and admirably 

 serves the purposes for which it was designed, especially in its 

 capability of being passed from hand to hand. An entirely un- 

 premeditated advantage has also been discovered in the ease 

 with which objects too bulky for examination on ordinary stands, 

 such as large minerals, natural history specimens, etc., can be 

 laid on the base-board (the stage being loosened and swung round 

 out of the way), and examined with this microscope over all 

 their surface. 



NOTES ON THE MICROSCOPE STAND AND ON SOME OF 

 ITS ACCESSORIES. 



AN AMATEUR. 



XV. 



THE SELECTION OF THE STAND. 



THESE chapters are expressions of personal preference in re- 

 gard to things microscopical. The expert microscopist ma}' 



