ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



799 



glass. Into this cylinder is screwed the body-tube of the Microscope 

 with eye-piece and objective, which are thus protected from the water 

 of the aquarium. The Microscope is focused by rack and pinion 

 (milled head just below the eye-piece), and in addition the objective 

 is screwed to a draw tube so that its position iu the cylinder may be 

 approximately regulated. 



The arm of the socket is hinged to allow of the Microscope being 

 inclined in a plane parallel to the sides of the aquarium. The lower 

 milled head clamps the hinge at any desired inclination. The socket 

 also rotates on the arm so that the Microscope can be inclined in a 

 plane parallel to the front of the aquarium. Thus any point of the 

 aquarium can be reached. 



Swift and Son's Oxyhydrogen Microscope. — This (fig. 129) 

 is suitable for use with ordinary objectives from 4 in. to 1/4 in. 

 The gas jet can be regulated for either parallel or convergent light 

 without the necessity of opening the lantern, it being mounted on 



Fig. 129. 



an independent pillar 2 in. from the back, and fitted to adjust to or from 

 the condensing lenses as occasion may require. The perforated metal 

 base renders it very liglit, and also allows the passage of a free 

 current of air, so that the lantern is kept as cool as possible. There 

 are three screws, upon which tlie whole is supported to finally adjust 



