of blowing up Mocks under Water, 117 
Observation . 
6th, This method has been often employed with ad- 
vantage in several mines of the republic : it may serve 
either for deepening wells, or making other excavations* 
when the means used for keeping the ground and bottom 
of wells constantly dry are insufficient. 
II. Method proposed for blowing up Rocks some Deci- 
metres below Water . 
7th, When the ground or rock to be blown up is co- 
vered only by some decimetres of water, the miner can 
«ee the rock which he bores, and the hole to be loaded, 
with as much ease as if there were no water, and can 
work with the same facility. In this case, to save ex- 
pense, the tube of tin plate may be omitted, and a car- 
tridge of pitched cloth, such as that employed in ground 
through which the water oozes in every part, may be em- 
ployed, adapting to it a rod of hollow wood * destined 
to contain the train that conveys the fire to the powder. 
The diameter of the aperture of this rod may be only a 
few millimetres, and its length must exceed the upper le~ 
vel by some centimetres. 
8th, If this method be adopted, first construct a cylin 
dric cartridge of cloth or pasteboard, and fill it with gun- 
powder ; insert into it the rod, which must descend to 
the middle of the length of the cartridge without ap- 
proaching the interior surface of the wrapper; pinch 
closely the upper part of the cartridge around the rod, 
and cover the cartridge and whole rod with pitch or some 
kind of varnish. f Then send down the cartridge fur- 
nished with its rod into the hole of the rock, and drive 
in strongly two plugs of dry wood to serve as wadding, 
* This rod might be made of the elder or honeysuckle. 
f A solution of Spanish wax in alcohol is attended with the advantage of 
drying speedily, and of remaining water-proof for a long time. 
