CHAPTEE IV. 

 ACCESSORY APPARATUS. 



The Lamp. 



It is most important that the microscopist should possess a 

 good and suitable lamp, otherwise he cannot work to the 

 greatest advantage. The amateur will often be found 

 working with a reading-lamp or an ordinary oil-lamp, but 

 good work can never be done conveniently by this means. 

 There are two or three important points which must be 

 borne in mind. In the first place, if light is proceeding 

 from the one illuminating point only, and the remainder of 

 the room is dark, while using the microscope, a great deal 

 better effect can be produced than if the whole room be 

 illuminated. In the next place, a small brilliant source of 

 light is far better than a large one. In recent years special 

 attention has been paid to this matter, with the result that 

 lamps have been constructed with which the best work may 

 be accomplished. The following are desirable features 

 which should be embraced by a good microscope lamp : 

 The reservoir for oil should be large in diameter and flat, 

 so that the light may be brought down very close to the 

 table. For this reservoir glass is usually preferable to 

 metal, it being much cleaner, and the worker is able to tell 

 when his oil is getting exhausted ; whereas with a metal 

 reservoir, unless careful reckoning is kept, in the middle of 

 some important observation the light may go out from 

 want of oil. A half-inch wick is generally found to be 

 sufficient. We strongly deprecate the use of glass chimneys. 



