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3)rav\)ino wttb Beale'£? 1RefIcctoi\ 



By G. H. Bryan, M.A. 



THE neutral-tinted glass reflector, or its simpler equivalent, a 

 cover-glass fixed at an angle of 45^ with the tube of the 

 microscope, would doubtless be used much more uni- 

 versally for drawing microscopic objects but for its radical 

 defect — that it gives a reversed drawing. This does not 

 matter, as a rule, when the drawing is finished, for, with 

 the exception of spiral structures (which would be changed from 

 right-handed to left-handed screws if drawn reversed), there are 

 few microscopic objects in nature of which a reversed drawing 

 would be an inaccurate representation. The difficulty comes in 

 principally when it is required to fill in the details of the drawing 

 by ordinary freehand, after the outline has been sketched out, for 

 it is impossible to trace the finer markings of objects by means of 

 the reflector, and when the latter is removed, the drawing will be 

 seen to reverse the object whichever way it is placed. How many 

 microscopists have thought of the simple expedient of substituting 

 for the plain glass reflector one silvered at the back, and then 

 copying in the details from the reflected image instead of removing 

 the reflector and looking straight down the tube? A correspondent 

 of Science Gossips some few years back, suggested another plan, 

 which may sometimes prove useful — namely, to lay the slide on 

 the stage cover downwards and sketch the outline with the reflec- 

 tor, and then to turn the slide the right way up and copy in the 

 details — an arrangement only possible, of course, with transparent 

 objects, and with low powers that can be focussed through the 

 thickness of the slide. 



If a glass reflector is used for drawing /^/(7m(r^/^/<r objects, it 

 must be remembered that the glass itself partially polarises the 

 light which it reflects, so that unless the analyser is turned in the 

 right direction the object will be almost, if not quite, invisible. 

 The great loss of light, which in any case results from such an 

 arrangement, may be entirely obviated by making use of the 

 polarising property of the glass reflector, and dispensing with the 

 analyser altogether. If the glass reflector, instead of being inclined 



