BOTTERILLS TROUGH AND LIFE-SLIDE. %7 



partition close to the front plate; Fig. 74 is not adjustable, 

 but is easily made by the student. 



Another adjustable form of trough is Botterill's, which 

 consists of two brass or ebonite plates bolted together, as 

 shown in Fig. 75, the plates of glass being separated, 

 according to the space required, by an ordinary indiarubber 

 ring of the requisite thickness. The trough can thus be 

 taken apart and the glasses cleaned, or a broken front 

 replaced without the trouble of cementing, the glass sides 

 being sufficiently thin to allow the use of high power 

 objectives. 



FIG. 75. 



A microscopic life-slide also devised by Mr. Botterill is 

 shown at Fig. 76 ; the advantages claimed for it are, the 

 facility with which it can be used and cleaned ; its reversi- 

 bility, allowing either side of the object to be examined 



FIG. 76. 



through thin glass ; the provision for renewing the supply 

 of water without disturbing any part of the apparatus, thus 

 enabling objects to be kept under examination for an 

 indefinite period ; the same arrangement also allowing of 



