38 



CONSTRUCTION OF THE MICROSCOPE. 



either simple lenses or doublets j or it could be easily con- 

 verted into a compound microscope by inserting a com- 

 pound body, supported on a bent arm, in the place of the 

 one carrying the single lenses. 



An arrangement devised by the late Mr. Quekett, for a 

 dissecting microscope, represented in fig. 25, is one of value 



i'lg. 25. — Quekett's Simple Microscope. 



and convenience. The instrument is made by Mr. Ladd 

 of Beck Street, and is furnished by him with three mag- 

 nifiers, namely, an inch, and half-inch, ordinary lenses, 

 and a quarter-inch Coddington ; these will be found to be 

 the powers most useful for the purposes to which this 

 instrument is specially adapted. The lenses, mirror, con- 

 denser, vertical stem, &c, all fit into hollows cut for their 

 reception on the under side of the stage, and are then 

 covered and kept in place by the side flaps : so that, when 

 packed together, and the flaps kept secure by an India 

 rubber band, the instrument is very conveniently portable. 

 The size and firmness of the stage afford great facilities 

 for dissection, and other scientific investigations. 



The Compound Microscope. — The compound microscope 

 may, as before stated, consist of only two lenses, while a 

 simple microscope has been shown to contain sometimes 

 three. In the triplet for the simple microscope, however, 

 it was explained that the object of the first two lenses was 



