26 PHOTOMICROGRAPHY 



their use. The soundest advice is to buy at the outset 

 the best stand that can be afforded, even if its price 

 involves the sacrifice at first of one or more lenses. 

 Convenience and pleasure in use, combined with accuracy 

 in the movements and good wearing qualities, well repay 

 the initial outlay, and further objectives can be added at 

 any time. 



The Stand. The first essentials in any microscope, 

 however simple or elaborate it may be, are freedom from 

 tremor, and rigidity in the vertical or horizontal positions 

 when clamped to the table or baseboard. Many stands, 

 even of the best makes, will fall forward when the tube is 

 placed horizontally, and it can hardly be claimed as 

 essential that they should not, as a clam> easily gets 

 over the difficulty, but at the same time it is a great 

 advantage to find a stand that will not require clamping. 

 Two types of foot are described in connection with the 

 illustrations, " Tripod or Claw " and " Horseshoe," the 

 former generally gives the more rigid support. The 

 horseshoe must be very substantial, with the single toe 

 projecting some distance behind the pillar, to give proper 

 support to a horizontal microscope. 



Microscopes are now very often finished in black, 

 instead of brass, and the appearance is very good. The 

 only thing that can be urged against the practice is that 

 the black may cover defects in brasswork, but we have 

 not known this to occur. 



The Limb. The shape of the arm which is attached to 

 the foot and carries the tube and stage is not of great 

 importance, provided that it holds the tube rigidly, but 

 it is very conveniently made in such a way that it can 

 be used as a handle for lifting the microscope without 

 risk of injury to any of the adjustments. Its size should 

 permit of large specimens being placed on the stage, 

 and allow for sufficient up-and-down movement of the 

 tube to focus 3" ^objectives as well as high powers. 



