68 



NOTE ON SOME PORTABLE MICROSCOPES. 



omitted it is that they either were not thought to come within 

 the limits of this note, or that they were overlooked. 



Taking them, then, in alphabetical order, the first that falls 

 to be considered is Mr. C. Baker's " Diagnostic 

 Microscope," a very compact little instrument, 

 made at the suggestion of Surgeon-Major Ronald 

 Ross for the use of officers in the I, M.S. for the 

 diagnosis of malarial fever, etc. The 

 annexed figure (Fig. 1) shows it as set 

 up for use. It is provided with rack 

 coarse and micrometer screw fine ad- 

 justment, sufliciently delicate 

 to focus a ^-in. oil-immersion 

 objective. The draw tube ex- 

 tends to 5 1 in. (160 mm.), and 

 the whole body can be 

 drawn up through the 

 bronzed jacket carry- 

 ing the rack adjust- 

 ment, so that powers 

 as low as a 2 -in. may 

 be used, which is very 

 convenient to natural- 

 ists and others who 

 require, on occasion. 



Fig. 1. 



low magnifications. 

 The chief dimensions of this instrument are as follows : — 



Eyepiece gauge, R.M.S., No. 1 = 0"9173 in. or 23*3 mm. 

 Substage gauge = 1^^ in. or 27*5 mm. 



Diameter of mirrors = 1;^ in. or 32 mm. 



Size of stage, 2 in. (50 mm.) x 2| in. (60 mm.). 

 Spread of feet 7 x 7 in. = 180 mm. 



The whole packs into a leather case, with handle or shoulder- 

 strap, which holds three objectives and an extra eyepiece, 

 measuring 10| x 3^ x 3 in. (270 x 90 x 75 mm.) 

 The stand alone in leather case costs £3 17s. Qd 

 A mechanical stage of a simple kind can be fitted if required, 

 but this not only appreciably raises the cost, it also necessitates 

 a somewhat larger case. 



