86 PRACTICAL TREATISE ON THE MICROSCOPE. 



quence of its low price, it being of a form which may be 

 added to from time to time, according to the wants of the 

 employer; thus, for instance, a vertical stand with two eye- 

 pieces, exclusive of the object-glasses, may be procured with- 

 out the stage movements or the fine adjustment, at the small 

 cost of £4 10s.; and as both the stage and the compound 

 body are of the same size in the vertical as in the perfect 

 instrument, the fine adjustment and stage movements may be 

 added to the former at any time, and render it as complete as 

 that represented by fig. 45. 



Tor convenience of package, the compound body may be 

 unscrewed from the arm, e, and the entire instrument, together 

 with condensing lens, forceps, animalcule cages, &c., be fitted 

 into a case seven-and-a-half inches high, six-and-a-half inches 

 broad, and five-and-a-half inches deep; or, if preferred, the 

 foot, a, may be removed from the uprights, 6, and the stage 

 being turned parallel with the axis of the tube, d, the whole 

 will pack in a flat box seven-and-a-half inches long, five-and-a- 

 half inches broad, and two-and-a-half inches deep. 



Mr. Ross has also made a small complete microscope stand, 

 which is a perfect model of the larger instrument. This, to- 

 gether with all the apparatus, is packed in a case nine inches 

 long, six-and-a-half inches wide, and three inches deep, and 

 forms a very compact travelling microscope. 



Besides the preceding instruments, Mr. Eoss has made 

 many other kinds. One of the best of these is described and 

 figured in the article " Microscope," in the Penny Cyclopcedia ; 

 this was the instrument having the middle-third of the com- 

 pound body supported by a triangular cradle on a beU-metal 

 arm, which suggested to Mr. Jackson the plan of attaching 

 the entire length of the body to an arm somewhat of the 

 same kind, but with dove-tailed slides, for it to move up and 

 down on. 



The stage which Mr. Eoss adapts to his microscopes differs 

 in some few respects from those employed either by Mr. 

 Powell or Mr. Smith: the movements are effected by two 

 racks and pinions placed at right angles to each other, and 

 either worked by milled heads placed underneath the stage at 



