108 Modern Microscopy 



They are always liable to get broken very easily, and 

 become a source of expense, in addition to which, if away 

 from town, there is a possibility of not being able to get 

 the right kind, and so work may be delayed. Far better 

 will be found the metal chimneys now made by nearly all 

 opticians, with a carrier for a 3 x 1 or 3 x IJ-inch slip. 



FIG. 40. MICROSCOPE LAMP WITH METAL CHIMNEY. 



It is obvious that if the slip be broken it can be immediately 

 replaced, it being part of the microscopist's average stock. 

 It is also desirable that the bar on which the lamp is raised 

 and lowered on the stand should be a square one. If round 

 in shape, the lamp is apt to swing round on the stand and 

 the whole to topple over. This is an impossibility with the 

 square bar. Such a lamp is shown in Fig. 40, by Swift 



