372 Intelligence and Miscellanies. 



ingenious kind, and is the invention of Mr. Hedge. So so- 

 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 of 

 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 

 Masting rocks, mahing 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, 

 18 29. — 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. Tlie holes being bored, he places a cork 

 upon the charge of powder, through which he passes a 

 double vvire, whose ends nearly meet, in a small cylinder of 

 glass filled with a compound of gunpowder and one tenth 

 of detonating silver ; the wires are secured in the cylinder 

 by bees wax. Thus prepared, he lowers the cork and wires 

 down till it meets the charge. Now supposing all the borings 

 thus charged, he puts about an inch of powdered rosin upon 

 the corks, and fills the remainder of the holes with melted 

 rosin. Then connecting one of the wires of each hole with 

 the outside coaling of an electrical jar, the others are so join- 

 ed as to receive the spark, which produces an instantaneous 

 explosion of the whole. He has tried this method in wood, 

 by boring augur holes, one in each 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^ 



