336 On the Cutting of Steel by Soft Iron. 



though they seem not to be pseudomorphous. The locality 

 is described, Vol. V. p. 249 of this Journal. They are 

 sometimes cover-^d with a very fine grained and close brown- 

 ish steatite, in which, as in the asbestus, the crystals leave 

 their form. The specific gravity of the crystals is less than 

 that given to steatite. In the various specimens 1 have 

 tried, it has been found very nearly 2, sometimes a little 

 more or a little less. Their specific gravity may be taken 

 at 2, water being unity. 



Art- XVIII. — On the Cutting of Steel by Soft Iron. 



Extract of a letter to the Editor, from the Rev. Herman Dag- 

 gett, Principal of the Foreign Mission School at Corn- 

 wall, Conn. 



Cormvall, Feb, 3, 1823. 



Dear Sir, 



I take the liberty to communicate to you a fact, which has 

 lately come to my knowledge, and which, I judge, may be 

 of considerable use in mechanics, and perhaps in philosophy. 

 It may not, however, be new to you. 



Mr. Barnes, (a cabinet-maker of this place) had occasion 

 to repair a cross-cut saw, (a saw to be used by two persons) 

 of a very hard plate, which would require considerable la- 

 bor, ir! the usual way of filing. He recollected having heard 

 that iho Shakers sometimes made use of what he called, a 

 buzz, to cut iron. He therefore made a circular plate of 

 soft sheet iron, (a piece of stove pipe,) fixed an axis to it, 

 and put it in his lathe, which gave it a very powerful rotary 

 motion. While in motion, he applied to it a common file 

 to make it perfectly round and smooth; but the file was cut in 

 two by it, while it received itself no impression. He then 

 applied a piece of rock-crystal, (a piece of which, he in- 

 forms me, he once presented to you,*) which bad the desir- 

 ed effect. He then brought under it, the saw-plate, which, 

 in -A few minutes, was neatly and completely cut through 

 longitudinally. When he stopped the buzz, he found it had 

 received no wear from the operation, and that he could im- 

 mediately apply his fingers lo it, without perceiving much 



*It was a peice of a very fine and large crystal of smoky quartz. — Editor. 



