262 MANIPULATION. 



CHAPTER II. 



ON CUTTING GLASS. 



Glass. — The best kinds of glass for mounting objects upon, 

 are those known in commerce as thin plate and flatted crown, 

 both may be purchased either in sheets or cut up into slides 

 ready for use ; if the former be preferred, it should be free 

 from holes and flaws, whilst, in the latter, veins and air 

 bubbles must be avoided ; should the operator wish to cut it 

 himself, he must be provided with a diamond of the form 

 represented in page 260, and a piece of apparatus termed a 

 cutting-board. 



Cutting-board. — This is represented by fig. 170, it consists 



'^'L 



\ 



9 



Fig. 170. 



of a piece of mahogany or deal, a b, about a foot or eighteen 

 inches long by eight or nine broad, and three quarters or one 

 inch thick ; upon this, and close to one of the sides, is screwed 

 a strip of similar wood, c, about an inch broad and one-fourth 

 of an inch thick, but not so long as the bottom piece by two 

 inches ; upon it may be marked lines, such as efg, to indicate 

 the width of the more common sized slides. The rulers are 

 generally made of the length of the board, and as broad as 

 the sizes of the glass-slides required to be cut, minus half the 

 thickness of the setting of the diamond ; the wood most suit- 

 able for them is from one-eighth to one-fourth of an inch 

 thick ; one of these rulers is represented by d. In aU, the 

 ends should be cut perfectly square, for a purpose presently 



