1012 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



Fig. 236. 



Giles's Army Medical Microscope. — Mr. G. M. Giles, Surgeon- 

 Naturalist, Indian Marine Survey, writes, that " to the military surgeon, or 

 explorer, who has to carry a Microscope with him, bulk and weight are 

 considerations of the first importance. Even in peace time the former is 



so often on the move, that he early 

 learns to dispense, as far as possible, 

 with bulky and heavy articles." 

 Hence he was "anxious to devise 

 an instrument which while it should 

 pack into a moderate-sized box, 

 should not be open to the objections 

 of some of the existing forms, and in 

 fact should be applicable to all the 

 work of the military surgeon in 

 station as well as in camp life." 

 This is shown in fig. 236. 



" The great obstacle in the way 

 of making a sufficiently portable 

 stand is that, in all previous patterns, 

 the stage is permanently fixed to the 

 body, and so has to be limited in 

 size in order not to unduly increase 

 the cross measurement of the box. 

 This difficulty has been met by 

 making the stage and foot in one 

 piece, arranged so as to fold up flat, 

 for packing (fig. 237), the body and 

 pillar being keyed on to the stage 

 and fixed in position by the arm 

 carrying the mirror being used as a 

 nut. 



When set up, the instrument is 

 about 9 in. high, and the stage 

 measures 2-6 in. by 2-2 in., and 

 is quite adequate to all ordinary 

 pathological work. When folded 

 up, it packs, including the centering 

 substage described below, into a 

 strong box 5*8 in. by 3 '2 in. by 

 2 "75 in. outside measurement. By 

 making the box a little longer 

 (7 inches) an extra objective, double nose-piece, and polariscope can be 

 carried in addition, the last-mentioned piece of apparatus being a special 

 desideratum to the geological explorer. 



Every microscopist knows how much definition is improved by the 

 use of the German form of diaphragm, the aperture of which is level with 

 the stage, and does not markedly exceed the field of the objective. In a 

 portable instrument, these can hardly be used except in a centering substage, 

 of which I have devised a very simple and inexpensive form for the purposes 

 of this instrument. It consists of a short, stout brass tube, screwing into 

 the opening in the stage. The tube carrying the diaphragms, polarizer, 

 condenser, &c,, is provided with a double collar, and is supported within 

 the larger tube by means of three screws. One of these has a thread only 

 at its point where it screws into the inner tube, its shaft working freely in 

 a hole in the outer. Between the two tubes it pierces a small piece of solid 



