130 THE AMERICAN MONTHLY [Aug 



See that your wick is quite dry, and that you have the 

 best paraffin ; dissolve one ounce of camphor in every 

 pint, fill your lamp about three parts full, light the wick, 

 and turn it till the flame is about three-quarters of an 

 inch high; allow it to burn for fifteen minutes, and then 

 turn it up as far as it will go without flaring or smoking, 

 let it burn for another five minutes, and if there is no 

 sign of smoking all will go well. The lamp should 

 always be turned with the edge of the flame to the mic- 

 roscope, the flat of the flame should never he used except 

 with a bull's eye. 



The camera need not be elaborate, if one is in use for 

 ordinary photography, no matter what size it is, it can 

 be used. But to those who do not possess a camera, it is 

 by no means diflicult to rig up an apparatus, which 

 though costing but a little will serve as well as a special 

 outfit. When a camera has to be made, make it of small 

 size, and it will be found that a quarter plate, 41 by 3^ 

 inch, will be quite large enough. The length of camera 

 is important, for upon the extension of the camera 

 depends the amplification of the image. It is advisable, 

 therefore, to have a camera which will extend to at least 

 4 feet 6 inches. It can be used either with or without 

 an eye piece. 



In making a camera, the first thing to do is to purchase 

 your dark slide. Cheap dark slides with a focussing 

 screen frame may be obtained, and it is advisable to pur- 

 chase the two because one of the main difficulties in 

 making a camera at home is to obtain perfect register 

 between the focussing screen and sensitive plate. The 

 camera- should be made in three sections, sliding one 

 within the other, and that portion nearest the microscope 

 should be the larger. A very stout varnished millboard 

 cHu be bought ; this is nearly a quarter of an inch thick. 

 Measure the exact size of your focussing screen frame, 

 which we will suppose to be 5J by 4J inches. We shall 



