30 REVIEWS. 



as merely writing for those who, with very limited means at their disposal, 

 are desirous of procuring a microscope to aid their researches. We wish 

 to give some idea of what would be a good way of procuring a good, plain 

 instrument for use, and at a moderate cost. Microscopes, as is well 

 known, are divided into simple and compound terms sufficiently well un- 

 derstood to need no definition ; the former may be divided into those used 

 in the hand, and those provided with a stand or apparatus for supporting 

 the object to be viewed. In choosing the latter, the principal points to be 

 attended to are, " to see that the stage is of sufficient size and strength, 

 and that the arrangements for holding the lenses, and moving them in 

 different directions, are convenient.'* 



Microscopes of this kind used for dissecting are furnished by all the best 

 makers. Of those we have used we prefer that furnished by Mr. Ross. 

 In this instrument the arm at the top, which carries the lens-holder, has 

 a forward motion, by rack and pinion, and a traversing motion, on a pivot, 

 by which means the lens can be carried in any direction over the stage. 

 It is usually furnished with lenses of one inch, half an inch, quarter of an 

 inch, and one-tenth of an inch focal lengths, and sometimes with a Wollas- 

 ton's doublet. For a figure of this instrument, accompanying the above 

 description, we must refer to the pages of Schacht's valuable manual on 

 "The Microscope, and its application to Vegetable Anatomy and Physiology." 

 For those who may not be disposed to purchase so expensive a form 

 of simple microscope, we can recommend the very portable one, called 

 " Quekett's Dissecting Microscope," lately produced by Mr. Highley. 

 Of this microscope the accompanying 

 figures will give some idea. Fig. 1 

 shows the instrument folded up, with 

 an Indian-rubber band round it, in 

 a manner which admits of its being car- 

 ried in the pocket. The two wedge- 

 shaped pieces of wood unfold, and form 

 the legs (see figs. 2 and 3). Fig. 2 

 shows the internal arrangement and the 

 manner in which the mirror, lenses, and lens-holder are packed away. The 

 straight flat bar, on the right in fig. 2, serves to keep the legs from closing 

 together, and also as a support for the mirror, which slides into a piece of 

 brass tubing, attached to the flat bar. The circular hole at the lower end 

 of fig. 2, is another piece of brass tubing, into which the lens-holder 

 slides. The instrument is furnished with three lenses, and is to be had at 

 a moderate price. 



