ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



485 



Fig. 139. 



metal plate on a wooden support. The former allows the axis of the Micro- 

 Bcope to be brought into line with that of the camera by moving it laterally 

 by hand ; it is also adjustable by three screws. The wooden support can be 

 freely moved to and from the camera, between guides on the base. 



The end of tlie camera which is turned to the Microscope has a long 

 brass nozzle, blackened inside, which carries a brass jacket moved by rack 

 and pinion. This jacket is inserted into a double cap fitting on the end of 

 the body-tube as shown in fig. 139. 

 A connection between the camera and 

 the Microscope is thus made which is 

 impervious to light. 



For fine-adjustment of the image 

 after a rough focus on the ordinary 

 ground glass, the latter is replaced 

 by a frame with a disc of transparent 

 plate glass having a cross ci^t with a 

 diamond in its centre. A low power 

 lens is focused on this mark and 

 moved over the plate by a carrier, and 

 the vaguely adjusted picture is then 

 accurately focused. 



In the smaller form of camera shown in tig. 140, there is a funnel- 

 shaped non-extending camera which is intended for use with an eye-piece, 

 as without it only small pictures can be obtained ; the camera is movable 

 between guides upon the wooden base. The plate-holders are 18 cm. 

 square. 



For a lamp is used the Siemens gas-burner on an adjustable brass stand 

 and glass globe, described in this Journal, 1886, p. 515 ; the lamp is said 

 to give an " excellent bright and white light which almost completely sup- 

 plies the place of good daylight." 



