OF MICROSCOPIC OBJECTS. 51 



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 upwards), 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 

 variety of apparatus may be attached to it. 



Mr. Loy employs the following arrangement for dissecting 

 insects or picking out Foraminifera, &c. : he fits an upright 

 brass rod into a heavy leaden foot, this rod carries a hori- 

 zontal arm bearing at its end a ring for holding a watch- 

 maker's eye-glass; in focussing it to his work, he presses 

 the eye-glass down with his head, the weight of the leaden 

 foot keeping it in its place, and allowing it to follow his 

 every movement. 



Again, a " condenser " is often required for the illumina- 

 tion 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 expen -ive. 



