4 
aa 
372 Intelligence and Miscellanes. 
ingenious kind, and is the invention of Mr. Hedge. So su- 
perior are the scales made at this establishment, that they 
are fast gaining, if they have not already acquired, the entire 
ascendancy in the market. 
There are none manufactured in this country or elsewhere, 
that can compare with them, either in cheapness, in style o 
finish, in the number of subdivisions, or in accuracy of grad- 
uations. We speak with more confidence of the superior 
accuracy of these scales, as we have thoroughly tested them 
in practice, and we know that the method of execution is 
such as to insure the greatest uniformity in all that are con- 
structed.—( Communicated.) 
11. Notice of a projected improvement in the method of 
blasting rocks, making tunnels through mountains, &c. with 
the result of some preliminary experiments—in a letter to 
the editor from a correspondent, dated New York, June 2, 
1829.—The projector conceives that a block of several tons 
might be separated from a large mass, at once, by making 
five or six blasts, tending like radii, towards the center of the 
block ; all the charges being fired at the same instant; but, 
as this cannot be accomplished by trains, he proposes to mix 
detonating silver with the gunpowder, and to apply it in the 
following manner. The holes being bored, he places a cork 
u 
explosion of the whole. He has tried this method in wood, 
by boring augur holes, one in cach of five logs, and it an- 
swers his expectations. 
By leave of the corporation, a trial has been made at Black- 
well’s island, where they are blasting rocks for the new Pen- 
itentiary. Five holes, each three feet deep, were made by 
the prisoners, at the distance of seven feet from each other, 
