OF THE MICROSCOPE. 51 



simply sliding the body through a tube or collar. In the higher- 

 priced stands the coarse movement is effected by means of a 

 rack and pinion, arranged as in the "Jackson " model, but in 

 both styles the fine movement is generally arranged in the 

 place where the coarse movement is located in the "Ross" 

 stand. These features \vill be found to characterize the micro- 

 scopes of Chevalier, Hartnack, Xachet, Zeiss, and others. 



The term "Continental" model has been applied by our- 

 selves and others to any low, compact form of microscope, but 

 a careful study of the subject has satisfied us that this is not 

 correct. The characters above given are peculiar to what 

 ought to be known as microscopes of the Continental model. 



The Continental model has some advantages on the score of 

 convenience, and as large numbers of our medical students 

 have been educated to its use, it has been such a favorite that 

 many of our prominent makers have imitated it to a certain 

 degree. For the ordinary work of the physician and the his- 

 tologist, a low microscope, which may be easily arranged for 

 work, and which may be used conveniently in a vertical posi- 

 tion, is certainly desirable, but other forms, possessing the 

 same advantages and without the objectionable features of the 

 Continental model, are now in market, and have taken their 

 place. 



The objections to the Continental model as a microscope for 

 the higher classes of work, are the want of space below the 

 stage for illuminating accessories, and the liability of the fine 

 movement to get out of order. For it is obvious that a very 

 little wear on the " ways " or "slides " will allow the body to 

 have considerable lateral motion, the distance of the "ways" 

 from the optic axis of the instrument being very great. Some 

 of our American makers, who have adopted this fine motion, 

 have gone so far as to use hard steel pins sliding on hardened 

 ways as guides, but with all their care lateral motion ensues 

 after a time. 



Tlie New American Model. The more general em- 

 ployment of objectives of wide angles of aperture, and of im- 

 proved methods of using them, have led American manufac- 

 turers to introduce certain improvements in stands of moderate 



