278 



CONTRIBUTIONS TO MICRO-MINERALOGY. 



plate of the lenses may be conveniently fitted with a small 

 moveable Tourmaline analizer. A stouter stand and stem, 

 carrying a Leeson's or Schmidt's goniometer, may be used in 

 place of the lens, for measuring the angles of large crystals. 



Fig. 2. 



As a Laboratory Microscope is subject to rough usage, an 

 economical form is certainly desirable ; the instrument, fig. 2, 

 1 contrived to this end. It is of a good size, substantial and 

 neat-looking, has a rack-work movement to the body, bulls- 

 eye condenser, with universal movement, and packs into a 

 case 8 inches by 6^ and 2f inches deep ; the whole being 

 purchaseable under three pounds. When the drawer is in the 

 case, the instrument is upright. I have adopted a novel mode 

 of bringing it into the inclined position in the cheapest way, 

 by cutting the sides of the box away to a convenient angle, so 

 that, when the drawer is removed, half of the top of the box, 

 being hinged, falls to the incline, as shown in fig. 2. 



For convenience in prosecuting the inquiries here laid 

 down, I deemed it necessary to construct an instrument that 



