POETABLE MICEOSCOPES 



245 



be used with this, there are very few but will be astonished at the 

 beautiful results attainable. Certainly, since the last edition of this 

 book was published, large and successful efforts have been made to 

 supply to those who need them cheap but thoroughly good micro- 

 scopes. 



Portable Microscopes. Microscopes that may be readily taken 

 from place to place, and which are yet provided with the arrange- 

 ments required for using 

 the principal apparatus, are 

 of importance in some in- 

 vestigations, and are de- 

 sirable by the majority of 

 those who have a living 

 interest in microscopic 

 work. 



The earliest and still 

 the best form of this kind 

 of microscope was made by 

 Powell and Lealand. As 

 opened for use it is illus- 

 trated in fig. 195 ; but the 

 tripod foot folds into what 

 becomes practically a single 

 bar, and is bent by means 

 of a joint to occupy the 

 least space. The body un- 

 screws, and the whole lies 

 in a very small space, giving 

 at the same time fittings in 

 the cabinet for lenses, con- 

 densers, and all needful 

 apparatus. The coarse and 

 fine adjustments to the 

 body are as in the No. 1 

 stand, so are the stage 



movements ; and the sub-stage has rack-and-pinion movements and 

 rectangular sector centring, while all the apparatus provided with 

 the largest instrument can be employed with it. We have used 

 this instrument for delicate and critical work for twenty years, and 

 there is no falling off in its quality ; and, when packed with the 

 additional apparatus required, the case is 12 x 7 X 3 inches. 



Swift and Son have arranged their Histological microscope 

 (fig. 196) as a portable instrument, to which from its peculiar con- 

 struction it readily lends itself, and must be placed in the third 

 class of portable microscopes. 



Mr. Rousselet has designed an admirable little instrument of 

 portable form but of the sixth class. It is binocular. The tripod 

 folds ; the stage is plain, with a sliding ledge. The condenser 

 focusses by means of a spiral tube, within which an inner tube 

 slides, carrying stops, diaphragms, &c. The mirror is jointed so as to 

 be used above the stage, and, as its focus is only 1^ inch, can be 



FIG. 197. Baker's diagnostic travelling 

 microscope (1896). 



