of blowing up Mocks under Water . life 
respect, that instead of wadding above the charge, ac- 
cording to the usual method, you employ an inflexible 
shank charged with a weight at its upper extremity, and 
terminating at the lower in a segment of an iron cylin 
der, which performs the office of a wedge, and is ap- 
plied exactly npon another similar wedge inverted and 
resting on the upper end of the cartridge. 
The effect of this disposition, as may he readily -con- 
ceived, is to force the wedge which adheres to the car- 
tridge to ascend a little at the time of the explosion, and 
to scpieeze itself closely against the upper wedge so as to 
close the hole in the rock. 
11th, The description of this process may be seen in 
the twelfth volume of the Memoirs of the Academy of 
Stockholm $ I shall therefore give a literal translation 
of it.* 
IY. JV\ 'ew Method of blowing up Mocks under Water , 
by Daniel Thunberg . 
A profile of the rock which has been bored, and into 
which the charge is introduced, is represented Plate 3* 
fig. 8. 
The charge is contained in a tube of tin plate imper- 
meable to water, a vertical section of which is represent- 
ed in the same figure. The lower extremity of this tube 
must be adjusted properly to the hole which has been 
bored in the rock. 
The charge consists of a paper cartridge filled with 
gunpowder, and attached to the iron wedge b with a 
thread such as that used for sewing sails. 
To this first wedge b is applied another c, which ad- 
heres to an iron rod that rises above the tube. 
* Details respecting* this process may be found also in a large work entitled 
Description des Travaux executes a Carlscrona , par Daniel Thunberg. 
