4:4: THE MI3ROSCOPE AND ITS REVELATIONS. 



foot, wherein is screwed a short tubular pillar (Fig. 31), which is ' sprung * 

 at its upper end, so as to grasp a second tube, also i sprung,' by the draw- 

 ing-out of which the pillar may be elongated to about 3 inches. This 

 carries at its upper end a jointed socket, through which a square bar 

 about 3^ 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 summib, and by sliding that bar through the 

 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 ap- 

 plied ; care being taken in all instances, that the ring which carries the 

 lens should (by means of its joint) be placed horizontally. At A is seen 

 the position which adapts it best for picking out minute shells, or for 

 other similar 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 



Ross's Simple Microscope. 



thereto, tne eye may be applied to it continuously without unnecessary 

 fatigue. It will be found advantageous that the foot of the microscope 

 should not stand upon the paper over which the objects are spread, as it 

 is desirable to shake this from time to time in order to bring a fresh por- 

 tion of the matters to be examined into view ; and generally speaking, 

 it will be found convenient to place it on the opposite side of the object, 

 rather than on the same side with the observer. At B is shown the po- 

 sition in which it may be most conveniently set for the dissection of ob- 

 jects contained in a plate or trough, the sides of which, being higher 

 than the lens, would prevent the use of any magnifier mounted on a 

 horizontal arm. The powers usually supplied with this instrument are 

 one of an inch focus, and a second of either a half or a quarter of an inch. 

 By unscrewing the pillar, the whole is made to pack into a small flat case,, 

 the extreme portability of which is a great recommendation. Although 

 the uses of this little instrument are greatly limited by its want of stage,, 



