282 Transactions of the Society. 



Cameras. 



In my work I have used the camera supplied by Messrs. 

 Nachet et Fils, of Paris, and have found it to be very useful. 



Modifications of the vertical cameras are prepared and sold by 

 nearly all Microscope makers. 



Horizontal cameras, designed specially for metallography, made 

 by Mr. Carl Zeiss, and Messrs. Beck, Limited, are much to be 

 preferred to the vertical type, the only objection being that they 

 take up much more space. 



Illuminators for Opaque Objects. 



As all metal objects are opaque, only such devices as throw 

 light on their surfaces are of use in metallography. 



The very excellent Sorby Beck oblique and vertical illuminators 

 for low power objectives, have done yeoman service to Micro- 

 metallography in the past, but I would suggest that they would be 

 still more useful if the silver mirrors were replaced by glass. 

 Except perhaps in country places free from smoke, fume and 

 grime, the silver surfaces become tarnished, and it is necessary 

 periodically to remove the reflectors and re-polish them before they 

 can be used. 



The internal cover-glass reflector of Beck has been used with 

 much success by most metallographers, but personally I have had 

 trouble in obtaining photographs when illuminating with this 

 arrangement, in consequence of the reflection of vertical rays of 

 light which fall on the surface of the lenses in the object-glass 

 itself. For this reason for several years I have used the Nachet 

 prism reflector, and more recently the prism reflector made by 

 Zeiss, which certainly gives illumination of a very high order and 

 is free from the objection inherent to the cover-glass. 



I notice that Messrs. Beck are now supplying a good prism 

 reflector for high power objectives which is fitted with a diaphragm 

 so as to cut off the light to any desirable degree. I have not had 

 an opportunity of trying this instrument, but hope to have that 

 pleasure in the near future. 



Messrs. Swift and Sons have prepared to my design a very 

 useful external cover-glass arrangement suitable for 1£ in. to 2 in. 

 objectives. This consists of a tube which is caused to slide over 

 the lower part of the object glass, the bottom part of which is 

 cut at an angle of 45°, and against this a cover-glass | in. 

 in diameter is placed and kept in position by small springs. The 

 inner side of the tube is blackened so as to avoid double reflection. 



