26 HOW TO SEE WITH THE MICROSCOPE. 



advantages ot the revolving stage are manifold, while 

 to the advanced worker, it is a sine qua non. In the 

 examination of difficult and resisting structures the ob- 

 server needs at times to employ almost every variety of 

 illumination, as well as to view the object under various- 

 aspects. In this department of work the rotating stage 

 cannot be dispensed with. 



Where money is an object, let the would-be purchaser 

 proceed with due care, giving this matter the closest 

 attention. By observing the following instructions he 

 can provide for a rotating stage capable of responding 

 to almost any call, and at an outlay not to exceed five 

 dollars. The writer has two stands. One is a large, 

 heavy, first-class instrument, and is, of course, furnished 

 with adjusting concentric stages, divided to half-degrees ; 

 the other is one of the smallest stands made, and is- 

 fitted with short tube (which can be drawn out to 

 standard length), and a plain, revolving stage, which 

 cost two dollars. Ninety-five per cent, of all his work 

 is done on the little stand; the work allotted to the 

 larger instrument being the measurement of the angles 

 of crystals, recording of objects by the Maltwood finder,, 

 and the measurements of the angular aperture of ob- 

 jectives. This much for the solace of those who are 

 bothered with the hard times. 



In making the selection with the view in hand of 

 providing a cheap rotating stage, the first important 

 point is to see that the instrument has sufficient stage 

 room. The stage should measure one and seven-eighth 

 inches from the centre of well-hole to the nearest por- 



