614 Transactions of the American Institute. 



done its work, falling from the plate into the fan, and is kept con- 

 stantly circulating. The pressure of this blast is not much more than 

 two or three ounces to the square inch. A pattern or design, or 

 stencil, as it may be called, is made of india rubber cloth, or of paper, 

 or the design may be painted on the surface to be cut ; the sand 

 striking these materials, which are elastic, rebounds, while it cuts into 

 the hard surface of the stone or glass. In many cases which were 

 tried with the use of high-pressure steam or air, a cast-iron register 

 front was used as a pattern ; a plate of glass three-eighths of an incr 

 thick and about fourteen inches square was cut through in fourteen 

 minutes. 



Woods of all kinds can also be cut or embossed, and for making 

 large letters or type for printing, this process will be expeditious ; the 

 harder the wood the more perfectly does the material cut. It may 

 readily be applied to the cutting out of coal ; its effect on such a 

 mineral would be like a jet of steam or hot water on ice, only to cut 

 coal with the sand-blast would be far more economical than to fuse 

 ice with steam. For cleaning or frosting silver this process will save 

 much time and expense. For cleaning castings, and preparing metals 

 for tinning or soldering, it is marvelously efficient. In its effect on 

 glass almost anything can be accomplished, from the cutting of a fine 

 engraving to the coarsest open scroll work; even steel cannot with- 

 stand its subtle action. In stone-cutting and ornamentation the 

 process is invaluable ; for, figuring or lettering in relief, the stone- 

 cutter must exercise the greatest care and patience, while this machine 

 will accomplish in half an hour what it now takes a man a week or 

 ten days to do. Prof. Coleman Sellers has written a very interesting 

 article on this process, which was published some months ago in the 

 Journal of the Franklin Institute. He mentions many curious facts 

 in regard to the action of the sand-blast on a variety of "surface. To 

 illustrate the extremes of its action, he states that, with a current of 

 air of light velocity, very delicate materials, such as the green leaves 

 of the fern, will resist the impinging of the sand long enough to allow 

 of their outlines to be beautifully engraved on glass, and that the 

 exposure can be so graduated that the thin parts of the leaves may be 

 cut through, while the veins and branches of the leaves resist, so that 

 a fine shaded engraving of the leaf is made; while with a high 

 velocity of steam, quartz sand will cut any substance harder than 

 itself. "With a jet of 300 lbs. pressure, a hole was cut through a 

 piece of corundum, which is next to the diamond in hardness, one 

 and a half inches in diameter and one and a half inches thick, in 



