ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



321 



MICROSCOPY. 



A. Instruments . Accessories, &c* 

 CI) Stands. 



Wilson's New Heating Stage.f — Leonard P. Wilson has constructed 

 a satisfactory heating stage with water as the medium. The stage (fig. 

 39) is in the form of a double box, forming a water-jacket to the slide 

 and its carrier. Water of the required temperature is passed in at A, 

 and flows out at B, the temperature being taken by a thermometer 

 passed into the tube C, round which the water passes in the middle of 

 its course. The heating stage is fastened to the mechanical stage by 

 means of the screw D. When using a high power, the objective passes 

 into the upper aperture of the stage, and is below the level of its upper 

 surface ; and, in order that the stage may move freely in all directions in 

 conjunction with the movements of the mechanical stage, it is necessary 



Fig. 39. 



Fig. 41. 



3B 



Fig. 40. 



that this tubular aperture be greater in diameter than the objective. To 

 prevent the intrusion of cold air, which might take place owing to this 

 difference in diameter, a vulcanite plate, having an aperture which the 

 objective just fits, slides on the surface of the stage under the clips E E. 

 In a manner similar to the objective, the condenser passes up into the 

 lower portion of the stage ; spaces for the vulcanite plate in this case 

 being made by the introduction of the two bars X X across the lower 

 surface of the stage, which is thereby raised above the mechanical 

 stage. The slide-carrier, as shown in fig. 40, consists of a brass plate, 

 having a circular aperture through it, and having fixed to it two springs 

 S S. By means of these springs, the slide is held in position on the 

 carrier, and the carrier is also held in position between the upper and 

 lower plates of the stage. The slide can be roughly adjusted by means 

 of the carrier, fine adjustment being made with the mechanical stage. 



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

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

 and Manipulation ; (6) Miscellaneous. f Knowledge, 1901, pp. 45-6 (3 figs.). 



