OF THE MICKOSCOPE. 55 



model, this microscope is provided with two draw-tubes, sliding 

 one within the other, so that the body may be shortened as 

 much as possible when desired. The first draw-tube has the 

 Society screw at the lower end, so that low-power objectives of 

 very great working distance may be used ; and as, by means of 

 the second draw, the draw-tube may be made of the usual 

 standard length (ten inches), it may be used as the body for 

 any objective, and quickly focussed by sliding it in the outer 

 tube, the same as in instruments without rack and pinion ad- 

 justment. The " broad-gauge " screw has been added, so that 

 low-power objectives of wide angle may be used to the greatest 

 advantage. 



Cheaper Stands. The stands which we have just de- 

 scribed, are, of necessity, somewhat expensive, because, unless 

 the workmanship is of the very best, the performance is quito 

 unsatisfactory ; and as a stand alone is of no use, an outfit 

 which includes such a stand is frequently beyond the means of 

 students and others. To meet the wants of such persons, the 

 various manufacturers we have named, together with Klein, 

 Pike, Schrauer, and others, have brought out stands, which, 

 when complete, with case and objectives, are sold for about 

 the price of the stands we have described. For the study of 

 elementary botany, histology, etc., many of these cheap micro- 

 scopes answer a very good purpose. They enable us to follow 

 the descriptions given in the books, and the view of any object 

 which we obtain from even the poorest of lliem, is infinitely 

 better than any representation which can be given by an en- 

 graving. The better class of these microscopes answer well for 

 the ordinary purposes of the physician, and, as they are simple 

 and easily used, they are frequently preferred to more expensive 

 and more complicated instruments. 



The Binocular Microscope. More than two hundred 

 years ago, attempts were made to construct binocular micro- 

 scopes, and yet a good and efficient binocular is a thing of 

 yesterday. The first really efficient binocular microscope was 

 constructed by Prof. Riddell, of New Orleans, about the year 

 1853, and to this fact Mr. Wenhani has borne free and generous 



