THE CAMERA, ETC. 47 



fixed so that a wheel, attached to the extremity next 

 the microscope, may always occupy the same position 

 beneath the fine adjustment, independently of the 

 distance of the camera from the platform. A silk 

 cord fastened round this wheel and the fine adjust- 

 ment, enables an observer, by turning the milled 

 head at the opposite end of the rod, to focus the 

 image on the screen of the camera when the adjust- 

 ment is beyond reach. An assistant is then un- 

 necessary, as no matter how intelligent he may be, 

 it will be found more satisfactory to have the focus- 

 sing under our own control. 



This method is a modification of that adopted by 

 Mr. Woodward when photographing without a 

 camera, under which circumstances we never use it, 

 having found the following arrangement much more 

 satisfactory. 



A cork with a slight rod attached to it by two wire 

 holdfasts, is slipped into a tube fastened to the fine 

 adjustment of the microscope; this enables us to act 

 directly on the fine adjustment without the inter- 

 vention of any cord or wheels ; unfortunately its use 

 is limited to those methods in which the microscope 

 is not attached to the camera. 



There is always great danger of the object and 

 objective being destroyed by the heat rays focussed 

 on them by the condenser. This may be partially 

 avoided by putting the condenser a little out of focus, 

 or we may entirely eliminate them by the interposi- 

 tion of a plate of alum between the bulFs eye conden- 



