936 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



Fig. 207. 



" disturbing influence of the warmtli of the observer's body," F. Miller 

 substitutes for the ordinary microscopic eye-piece a telescojie adjusted 

 to parallel rays whilst the object is in the focus of the objective of 

 the Microscope. The distance of the eye-piece of the telescope 

 from the objective of the Microscope is immaterial ; the image of 

 the object always appears sharply defined. 



Salt's Pocket Microscope * (Swift-Brown Pocket Microscope). — : 

 We take from the 'Lancet' the following description (modified to 

 meet subsequent alterations) of a small j^ocket Microscope, by Salt and ] 

 Son of Birmingham (Fig. 207) for the examination of m-inary deposits,] 

 blood, &c. 



" The stand and mirror hitherto deemed essential in all compound ' 

 Microscopes are dispensed with. A lens is placed at the end of the 



Microscope, which when the instru- 

 ment is held up to a window or 

 lamp, concentrates sufficient light 

 upon the slide to render all objects 

 in the field distinctly visible. Even 

 on a dull day in London we have 

 found the illumination thus obtained 

 amply sufficient. The Microscope 

 is a compound achromatic one, 

 furnished with a ^-inch objective 

 having a magnifying power of 120 

 diameters, and a sliding tube of 

 short range for adjusting the focus. 

 In using the instrument it is intended 

 that a few drops of the suspected 

 urine are placed between two small 

 glass slides, which are then placed 

 in a deep notch in the lower part 

 of the Microscope. They are fixed 

 in situ by a sliding tube [ordinarily 

 pressed downwards by a spring, but 

 which can be withdrawn within the 

 upper tube (by the projections 

 working in slits on either side) 

 when it is desired to change the object]. The Microscope is then 

 applied to the eye, as shown in the engraving, and the focus adjusted. 

 " It is an ingenious little instrument, very compact, measuring only 

 five inches in length, and its case is scarcely bigger than that of a fair- 

 sized urinometer. We can thoroughly commend it not only for conveni- 

 ence, but, when properly used, for efficiency also. It is well adapted for 

 the examination of the blood ; an excess of white corpuscles can be at 

 once distinguished by its means. It is also, when properly employed, 

 very useful for the examination of the urine ; but used in the method 

 recommended by Messrs. Salt, it is almost valueless for this purpose. 

 It is true that if a urine were loaded with pus, this could no doubt be 



* 'Lancet,' Jan. 29, 1881, pp. 188-9 (1 fig.). 



