ZOOLOGY AND BOTANY. MICROSCOPY, ETC. 



113 



Fig. 4. 



to leave the funnel unchanged for its ordinary use with the reflector, 

 and also to enable it to be easily cleaned. 



To use the instrument the funnel, with or without the additional 

 tube, is placed in the ear and its position arranged by means of an 

 ordinary reflector for viewing the interior of the ear. The Microscope 

 is then carefully pushed down into the socket until the image is sharply 

 defined. By moving the instrument to and fro it is possible to obtain a 

 view of every part of the external meatus which can be seen by the naked 

 eye, and its use presents no difiiculty even to the novice. 



The field of view is not contracted by the prism over the objective, 

 but the light is halved in intensity. The lens-openings are, however, 

 made so large that the brightness of the image is quite sufiicient. The 

 illumination is of course most intense over 

 the whole field of view when the lamp is 

 as near as possible to the prism, but regard 

 for the ear and cheek of the patient places 

 a certain limit to the approach of a hot 

 source of light. The lamp and illumi- 

 nating lens must be so arranged that only 

 the part of the object appearing in the 

 field of view is illuminated, but this as 

 uniformly as possible. The proper arrange- 

 ment is easily obtained by trial. 



Moreau's Monkey Microscope. — This 

 Microscope (fig. 4), by M. Moreau of 

 Paris, was exhibited at the December meet- 

 ing of tlie Society. In its design Art as 

 well as Science has been drawn on, for in- 

 stead of an ordinary base and pillar a figure 

 of a monkey is introduced which holds in 

 its hands the stage and mirror, while the 

 cross-arm carrying the body-tube and socket 

 is screwed to the top of its head ! 



Crouch's Petrological Microscope. — Messrs. Henry Crouch, Limited, 

 have constructed an instrument on the model of that of MM. Nachet, in 

 which the stage and objective rotate together with the upper part of the 

 body-tube, while the eye-piece remains stationary. It is not, therefore, 

 necessary to centre afresh with every change of objective. 



Among other points is the device for the convenient focusing of the 

 substage condenser when convergent polarized light is employed. The 

 lenses are placed in the tube of the polarizer and are then thrown in 

 and out of the line of light at the same time as the polarizer, by merely 

 moving the bar on which both are mounted. A milled ring above the 

 polarizer focuses the condensers by a single rotating movement, similar 

 to that by which the polarizer itself is rotated. Two analysers are pro- 

 vided, one in the eye-piece and the other in a draw-box above the 

 objective.* 



Reichert's Petrological Microscope. — Herr C. Eeichert's Petro- 

 logical Microscope (fig. 5), constructed for the Vienna Mineralogical 

 Institute, has two specialities. 



* Cf. MiiAvcr's 'Primer of Micro-petrology,' Svo, LouJou, 18S8, pp. 64-6 (1 fig.). 

 1889. I 



