Blasting of Rocks—Danger and Remedies. 137 
used, it is still much less than is required to charge in the old method, 
as_described by Mr. Catlin. Should this method, on further trial, 
be found to be sure and effectual, it will afford as full a remedy, as 
ean perhaps be expected, for the hitherto hazardous nature of the 
employment. With the most respectful consideration, 
I am, Sir, your friend and servant, 
Eni W. Buaxe. 
Ill. Letter of the Editor to Dr. Catlin. 
Dear Sir—It is perhaps hardly necessary to add any thing, after 
the able and clear instructions, given by Mr. Blake. But as people 
are more prone to go-on as they have been accustomed to do, than 
to adopt new modes, although improved ones, it may not be amiss 
to say, that Mr. Blake’s method appears to me, to embrace all the 
desiderata, both theoretical and practical, which the case requires. 
1. You are aware that the explosion of gunpowder, arises from 
the instantaneous production of a vast quantity of gases, which be- 
ing also expanded by the red heat, cannot be confined, and of course, 
‘when not permitted to escape, rend their enclosure. With a given 
quantity of powder the tendency of the gases to rend the enclosure, 
is increased, in proportion as we increase the resistance which we 
present, tending to prevent their escape ; and we modify this re- 
sistance, to suit our views, in different cases. In a gun, we add 
4 wad, not only to retain the powder, but to cause its more instanta- 
heous combustion, and to confine the action of the gases in that di- 
rection, to the bullet; it is not our object to do more, and if our charge 
"1s too great ; or the wadding is rammed down too hard ; or there is 
upon it, too great a load of metal, the reaction is so violent, as to burst 
the piece. This is a rare accident, considering how many discharges 
are made by careless people ; and we are scarcely aware how much 
the force of an explosion is increased by even slight resistance.— 
A train of gunpowder laid on a board, burns, as we know, with so 
little rapidity, that we easily walk or run faster than it goes ; but, if 
another board be laid over the train, and weights placed upon It, al- 
though still open at the sides, the powder then burns with amazing 
rapidity. Powder merely flashes in the pan of a musket, but the 
same powder placed in a quill, burns vehemently ; still more, fulmi- 
nating mercury, which also flashes, (although with intense brightness, ) 
when fired in a heap, explodes with great violence, in a quill. 
Vor. XVII.—No. 1. 18 
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