26 PREPARATION AND MOUNTING 



very well.) In the centre of a round piece of tough board, three 

 inches in diameter, make a hemispherical cavity to fit half of the 

 ball, and bore a hole through from the middle of this cavity, to 

 allow the wire to pass. Take another piece of board, about four 

 inches in diameter, either round or square, and one-and-a-half or 

 two inches thick, make a similar cavity in its centre to receive the 

 other half of the ball, but only so deep as to allow the ball to fit 

 tightly when the two pieces of board are screwed together, which 

 last operation must be done with three or four screws. Let the 

 hole for the wire in the upper part be made conical (base up- 

 wards), and so large as only to prevent the ball from escaping 

 from its socket, in order that the shaft may move about as freely 

 as possible. Turn a cavity, or make holes, in the bottom of the 

 under piece, and fill with lead to give weight and steadiness. 

 This, painted green bronze and varnished, looks neat ; and by 

 having pieces of gutta-percha tubing to fit the shaft, a great vari- 

 ety of apparatus may be attached to it. 



Again, a " condenser" is often required for the illumination of 

 opaque objects. My ingenious friend uses an " engraver's bottle" 

 (price 6d.), fills it with water, and suspends it betwixt the light 

 and the object. Where the light is very yellow, he tints the 

 water with indigo, and so removes the objectionable colour. 



I merely mention these as -examples of what may be done by a 

 little thoughtful contrivance, and to remove the idea that nothing 

 is of much value save that which is the work of professional 

 workmen, and consequently expensive. 



