[ 40 ] 



a Camera Xuciba for Botbing. 



By J. W. Plaxton. 



THE other day, after a morning's work, something went wrong 

 with the prism of my camera kicida, and, do what I would, 

 I could not bring it back to usefulness. At a loss for the 

 moment, I cast about for a substitute, and in half-an-hour, with 

 penknife and pencil, out of a piece of stiff paper and a square of 

 thin glass, had turned out a fragile but efficient substitute for what 

 is known in catalogues as " Beale's Neutral-tint Glass Reflector," 

 price 6s. 



This is how I did it : — Describe a circle by standing the eye- 

 piece of the microscope on the paper and running a pencil round 



it; inscribe a square in the circle already 

 drawn by drawing the pencil along the 

 edges of the square of thin glass you 

 intend to use ; now lay down the 

 diagonals of the square ; draw three 

 other lines within the square, each one 

 parallel with a side of the square, and 

 each, say, one-eighth of an inch from 

 the side ; draw two other short lines 

 {a.a. in the diagram) parallel to the 

 diagonals. 



Take the penknife, and, following the continuous lines of the 

 diagram, cut through the paper. You will have, in paper, what 

 resembles a three- spoked wheel without tire. The upper triangle 

 of the four within the square falls away as useless; the lateral 

 triangles open outwards, and stand at right angles with the plane of 

 the circle ; the little flanges on their lower edges are made by 

 creasing the paper to support the thin glass. The base of the 

 lower triangle answers the same purpose. 



Put the eyepiece in the microscope, the circle of paper to the 

 end of it : turn the spokes of the wheel back along the tube, and 

 slip a tiny elastic band over them, or tie them with a thread ; a 

 little manipulation with the fingers, the thin glass is in place, and 

 the thing is done. 



