ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 595 



MICEOSCOP\^. 



A. Instruments, Accessories, etc.* 

 (1) Stands. 



New Spencer Microscope, No. S.f — The body-tube of this instrument 

 (fig. 34) is of akiminium, and is arranged to accommodate the large 

 low-power photo-micro-objectives as well as those with the Society 

 screw ; the oculars are compensating, with lenses of large field. The 

 large arm is conveniently shaped for handling, and has the Spencer side 

 fine-adjustment. There is a free distance of 100 mm. from optical axis 

 to arm. One complete revolution of the thread represents an up-and- 

 down movement of O'l mm., and the graduations on the button to 

 100 parts make the value of each division one micron. The revolving 

 stage is 150 mm. in diameter, the vulcanite area being of 130 mm. in 

 diameter. The nickelled periphery is graduated to degrees, and the 

 vernier reads to three minutes. The mechanical stage is easily 

 removable by simply slipping it off from its bearings, which are 

 embedded in the stage. The bearings may then be covered by a slide 

 provided which makes a clear, even, plane stage without the necessity 

 and expense of buying an extra plane stage. The buttons operating the 

 mechanical stage are on concentric axes, one above the other. There is 

 a range of 80 mm. in lateral movement and 50 mm. in to-and-fro 

 movement. When the large stage is centred liy means of the centring 

 screws the two vernier readings of the mechanical stage are all that are 

 necessary to locate an object. The complete rack-and-pinion sub-stage 

 is equipped with an achromatic condenser fitted on the drop-swing 

 mounting. 



Spencer Microscope, No. 10. J — This instrument (fig. 35) very closely 

 resembles the No. 5 of the same firm. The chief differences are : (1) in 

 the shape of the arm, with its handle opening; (2) in the lateral 

 movement of the stage, 75 mm. as compared with 80 mm. ; (3) in the 

 free distance between the arm and optical axis, 80 mm. as against 

 100 mm. 



* This subdivision contains (1) Stands : (2) Eye-pieces and ObjectiTes ; (3) 

 Illuminating and other Apparatus ; (4) Photomicrography ; (5) Microscopical 

 Optics and Manipulation ; (6) Miscellaneous. 



t Catalogue, Spencer Lens Company, p. 15. 



t Catalogue, Spencer Lens Company, p. 15. 



