STANDS OF MEDIUM PRICE. 17 



can be set to any angle of inclination, the plate being 

 divided so that the angle may be recorded, and in this way 

 also, light of any degree of obliquity may be used without 

 interference from the thickness of the stage. Horizontal 

 movements by two milled heads are capable of being 

 imparted to the stage, which may also be revolved by 

 means of a milled head, or when this is pulled out, by 

 using the two ivory studs fixed to the top plate for that 

 purpose. 



For a description of the substage, we must refer our 

 readers to a later portion of this chapter, wherein special 

 forms of instruments are described, and in concluding a 

 notice of these microscopes, urge every one who is wishful 

 to possess a first-class instrument to see the work of each 

 of these three firms before deciding. One cannot be too 

 careful in the selection of an instrument, and we have nearly 

 always found that if any one has rushed blindly into the 

 purchase of a microscope on the recommendation- of a 

 friend, sooner or later he has been dissatisfied with it, and 

 has finally purchased another of his own choice. 



Other opticians produce as specialities good working 

 stands at a medium price. 



Swift's " Challenge Binocular " is shown at Fig. 8, and 

 has been in especial favour during the past few years ; it is 

 a good working instrument, especially when combined with 

 his universal substage condenser. The general construction 

 of the stand will be seen on reference to the figure ; it is 

 not too tall or large, and is exceedingly well balanced. 



Collins* " Harley Binocular," though formerly made upon 

 the Ross model, is now constructed upon the Jackson 

 model, and has this advantage, that commencing with 

 a simple stand, a very complete instrument, such as 

 shown by Fig. 9, can be built up from it. The stage is 

 made to rotate and also to move by means of milled heads 



c 



