54 



PEACTICAL TREATISE ON THE MICKOSCOPE. 



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When portability is studied, a very convenient and useful 

 microscope, for many purposes, can be readily made with one 

 or both of the pocket magnifiers, before described at page 48, 

 if either of the two forms, as there represented, have a hole 

 in the handle. These being provided with a stand, as repre- 

 sented by fig. 33, of 

 any convenient size, 

 from which a small 

 stem rises, the pocket 

 lens may be made to 

 — slide up and down this 

 ' stem, and if required 

 to be fixed at any 

 given point, a small 

 screw wiU suffice for 

 the purpose. 



This method of 

 mounting the pocket 

 lens on a stand was 

 first suggested by 

 Mr. Lister, and has 

 been carried out by 

 Messrs. Smith and 

 ^ig 33. Beck ; but as the plan 



adopted by them, represented by fig. 33, is rather dififerent 

 from that just described, it will be requisite here to give an 

 account of their improvements.* Their pocket magnifiers have 

 a square hole in the end, and they use a circular stand, and 

 on the stem, which is round, a piece of brass is made to slide 

 up and down, carrying a binding screw on one side, and a 

 small arm on the other ; this arm is straight for about a fourth 

 of an inch, and then is bent at a right angle for about the 

 same length, the last part is square, and upon the square, the 

 magnifier is made to fit ; this is a much better plan than the 

 former one, in which the screw for tightening is in the end of 

 the handle of the magnifier, as less trouble is required in 



* By an error of the artist, the magnifier is represented the wrong 

 f:'ide upwards. 



