ZOOLOGY AND BOTANY. MICROSCOPY, ETC. 



509 



MICROSCOPY. 



A. Instruments, Accessories, &c* 

 (1) Stands. 



Pfeiffer's New Preparation Microscope. — This has been designed 

 by Prof. Pfeiffer to meet a want felt by him in his work on malarial 

 parasites. He considered that an instrument of this kind should give 

 an erect image, a maximum object-distance, large field, and sufficient 

 magnification. 



Fig. 123 shows the Microscope, which is built on the ordinary prin- 

 ciple, but the inverted image produced by the objective is by a suitable 

 prism arrangement presented to 



the eye as erect. These prisms Fig. 123. 



are contained in a somewhat 

 wide brass tube, which on its 

 under side carries the objective 

 excentrically, and on its upper 

 the ocular. The bending of the 

 light-path shortens the tube 

 length, so that the eye is only 

 13—15 cm. above the stage on 

 which the hands work. Three 

 objectives are supplied ; No. 1 

 gives 32-fold magnification at 

 45 mm. object distance ; No. 2, 

 44-fold at 25 mm. ; and No. 3, 

 65-fold at 15 mm. In spite of 

 the passage of the light through 

 the prisms, the image is full of 

 light, sharp, and free from chro- 

 matic defects. The optical part 

 is mounted on a firm stand with 

 rack and pinion ; the stage is 

 spacious, and has supports for 

 the hands. The stage-opening 

 is provided with iris diaphragm, 

 and the whole instrument can 

 be very conveniently packed into a light box. 

 Leitz. 



Erection of the microscopic image by means of prisms was first 

 effected by Ahrens.f The same idea was carried out "by Zeiss in 18954 



Vernier Microscope. — The Microscope shown in fig. 124 is of the 

 type known as the Vernier or Micrometer Microscope. It was designed 

 in the first instance for Prof. Baily of the Heriot-Watt College, and 



* This subdivision contains (1) Stands; (2) Eye-pieces and Objectives; (3) Illu- 

 minating and other Apparatus ; (4) Photomicrography ; (5) Microscopical Optics 

 and Manipulation ; (6) Miscellaneous. 



t Cf. this Journal, 1888, p. 1020, fig. 161. 



X Cf. this Journal, 1895, p. 580, figs. 82-81. 



Aug. 15th, 1900 2 M 



The maker is Herr 



