ZOOLOGY AND BOTANY, MICEOSGOPY, ETC. 



935 



The specialty of the instrument consists, it will be remembered, in 

 attaching the eye-piece to a separate immovable arm, the body and 

 stage rotating independently beneath it and above the fixed polarizer. 

 This contrivance is retained in the new form, which has the following 

 additions : — A small mirror M is placed immediately below the eye- 

 piece, so as to illuminate the cross wires when the field is dark. The 

 whole of the tube from A upwards is attached to the fixed arm, and is 

 moved by a separate rack and pinion. The analyzer is inserted at A, 

 and can be readily withdrawn when required. At B is a slit for the 

 introduction of f)lates of quartz, &c. The stage is more elaborate, 

 and has a traversing object-platform D rotating in the optic axis by 

 the pinion E, or by hand. The polarizing prism N is not attached 



Fig. 206, 



to the stage, and can be centered by the screens C and C. If it is de- 

 sired to use the instrument as an Amici Microscope, a cone with con- 

 verging lenses can be fitted into the end of the eye-piece tube, the 

 latter being raised or lowered by the upper rack-and-pinion movement. 

 A smaller form on the same principle is shown in Fig. 206. 



Miller's Microscope with Telescopic Eye-piece.* — "In order to 

 " view objects at any distance that may be required, and so obviate the 



* Centr. Zeit. f. Opt. u. Meet., ii. See Zeitschr. f. Instiiunentenk., i. (1881) 

 p. 210, 



