198 FIRESIDE SCIENCE. 



the smaller passing through the orifice, to the bot- 

 tom, being fine enough to perform their functions 

 on the polishing wheel. The coarser grains are 

 afterwards, as we have stated, powdered in a steel 

 mortar. Diamond cutting is slow and tedious work, 

 and requires the utmost care and skill to accomplish 

 the process successfully. In the Boston factory, 

 the labor is done under the eye or immediate super- 

 vision of Mr. Morse, who originated the industry, 

 and who devised and constructed the machinery. 



The diamond has a grain or cleavage plane, the 

 same as most mineral or crystalline substances, and 

 hence it is possible to split or divide one into two 

 or more parts. Sometimes a large piece is removed 

 at once from a gem by splitting, but it is a process 

 attended with much risk. To accomplish this after 

 the stone is carefully studied and its line of cleavage 

 ascertained, it is placed in hardened cement, in the 

 proper position, and the sharp edge of a steel chisel 

 resembling a razor is carefully adjusted so that the 

 division will be at the points desired, and a smart 

 rap with a hammer is given it. Perhaps no more 

 costly blow may be struck in any mechanical work 

 than this, for in manipulating a large diamond, if it 

 is unskilfully given, a gem of several thousand dol- 

 lars' value may be spoiled. 



After a diamond is cut, the work of polishing 

 commences, and it is in this department that the 



