HAND- MAGNIFIER ROSS'S SIMPLE MICROSCOPE. 91 



FIG. 14. 



variety of positions suitable for dissecting and for other manipu- 

 lations. It consists of a circular brass foot, wherein is screwed 

 a short tubular pillar (Fig. 14), which is " sprung" at its upper 

 end, so as to grasp a second tube, also " sprung," by the drawing 

 out of which the pillar may be elongated to about three inches. 

 This carries at its upper end a jointed socket, through which a 

 square bar about 3 J inches long slides rather stiffly ; and one end 

 of this bar carries another joint, to which is attached a ring for 

 holding the lenses. By lengthening or shortening the pillar, by 

 varying the angle which the square bar makes with its summit, 

 and by sliding that bar through its socket, almost any position 

 and elevation may be given to the lens, that can be required for 

 the purposes to which it may be most usefully applied ; care 

 being taken in all in- 

 stances, that the ring 

 which carries the lens 

 should (by means of its 

 joint) be placed horizon- 

 tally. At A is seen the 

 position which adapts it 

 best for picking out mi- 

 nute shells or for other si- 

 milar manipulations; the 

 sand or dredgings to be 

 examined being spread 

 upon a piece of black 

 paper, and raised upon a 

 book, a box, or some 

 other support, to such a 

 height, that when the 

 lens is adjusted thereto, 

 the eye may be applied to 

 it continuously without 

 unnecessary fatigue. It 

 will be found advantage- 

 ous that the foot of the 

 microscope should not 

 stand upon the paper 

 over which the objects 

 are spread, as it is de- 

 sirable to shake this from 

 time to time, in order to 

 bring a fresh portion of 

 the matters to be ex- 

 amined into view; and, 

 generally speaking, it 

 will be found convenient 

 to place it on the opposite Ross ' s simple Micros 'pe. 



side of the object, rather than on the same side with the ob- 



