74 THE AMERICAN MONTHLY [Mch 



Two pieces of cardboard of the same^ixe should be cut 

 to go underneath when required ; both should be covered 

 with black paper, and one should have a hole about li 

 inches in diameter in the centre. The whole stand might 

 be made of wood f inch thick, mahogany being prefera- 

 ble to pine, and the dovetailing or grooving should be 

 finished as carefully as possible. 



The holder for the lenses can be made, by fitting a piece 

 of i-inch brass tube about 8 inches high into a small 

 stand, say, 2£ inches in diameter. A piece of springy 

 i-inch brass wire is then rolled several times tightly 

 round the upright as shown ; one end is tured up about 3 

 inches away from the stand, and the other end is shaped 

 into a ring to hold a watchmaker's eye-glass. This last 

 can be bought anywhere for 25 cents, and makes a most 

 useful dissecting lens. On the turned-up end can be put 

 an ordinary pocket-magnifier in ebonite mount, such as 

 can be bought for 25 cents and upwards, according to 

 the number of lenses. 



This stand, simple though it be, will be found a useful 

 and efficient piece of apparatus. It will be money well 

 spent, however, if the beginner provides himself at the 

 outset with one of the beautiful aplanatic lenses sold by 

 all the principal opticians. They give exquisite definition 

 together with a flat field, are excellent for dissecting,and 

 are also the most perfect of those magnifiers which the 

 real microscopist can always bring forth from his pocket 

 when wanted. The most useful powers do not exceed ten 

 magnifications, and a lower power gives a larger field and 

 greater working distance. 



For dissecting requiring to be done under water or 

 methylated spirit, a piece of cork loaded with lead is use- 

 ful ; or a mixture of paraffin and stearinemay be run into 

 the bottom of the dissectiug-dish. This paraffin mixture 

 is transparent, which is generally an advantage ; but 

 where an opaque background is needed a mixture of beeg- 



