, 1877-11-30
THE USE OF DfRAElTE FOR gsia'H'
ING SPECIMENS OF FISH AT SEA-
I.y James a.. swan.


with giant powder, which the boys
frequently used, to see their effects
an the fish around the piles at the
end of the wharf. The effect was
generally more than was contemplat'
ell, and the quantities OF hsh k'IIeu,
stunned or scared away, soon made
the use of the explosives nuisance
which by common consent wasabated,
and the practice abandoned. 1t has
been found, however, that for sclen-
ti6c purposes and to procure specl-
mems of fish that lie in deep water,
never take bait, and never rise to
the surface, that the cartridges are
very effective. :.
Professor George Davidson, Presi
dent OF the California Academy OF
Sciences, has kindly forwarded to me
copy of q paper on this subject,
which was prepared by A. W. Chase,
ESQ, U. S. Coast Survey, and read
before the Society, July 6, 1874, and
from which will make few extracts:
Giant powder No. /, or dynamite,
is simply nitro.glycerine, with the
addition of an absorbent earthly pow
der, an infusorial earth obtained in
Europe, being the principal material
used in the California dynamite
works. This preparation has the ap'
pparance aud consistency Of soft putty
and is put up in cartridges esembling
All ordinary candle bat Of various
sizes, according to the purposes for
which tits to be applied. In using
it for explosion in deep water, the
cap is 6tted on the end Of the fuse,
and both buried deep in the putty
like explosives; a string being
then tied tightly around the fuse
where it comes in contact with the
edges of the paper wrapper, the
top is then tallowed and it is ready
Tor use.
The experiments Of Mr.. Chase, off
Catalina Island, Southern California,
showed that the ordinary water. proof
fuse will burn about one foot to every
twenty FIVE seconds, and that cart.
ridge will explode in from four to six
fathoms of water, with from three to
-four inches of fuse. The shock of
the explosion is most severely felt
downwards, as the resistance is great.
er; and the different varieties of sea
fish found near the rocky shores, be-
ing as general rule on or near the
bottom, it is desirable to explode the
cartridge about midway between the
surface of the water and ths rocks be.
meath, as the deep.lying fish Ind those
which swim between are bothireacbei.
The method Of operation at Cata
lima Island, is thus described by Mr..
Chase: 81 would pull off in a
small skiff to the kslp beds that sur
r,und the island. Here in six or
eight fathoms of water, the bottom is
distinctly visible, owing to the abb
sence of currents or sedimentary de-
posits around the rocky shores, which
render the water beautifully clear
and limpid. Fastening my skiff to
the floating weed, ! would part the
stems and look into the depths below.
1t is a most wonderful and interest
ing study. You see the stems of kelp
rising from the bottom like twisted
pillars, often many being twined to-
gether. Through these submar ne
forest aisles are seen great @pmbers
of fish and crustacea of various kinds.
When an unusually large school of
fish would swim by, l would quietly
light the fuse and drop the cartridge
into the water gently. II the water
was, say eight fathoms deep, would
graduate the fuse for explosion at
four fathoms. The cartridge would
slowly sink--generally in a spiral
and few bubbles OF air or smoke
arise to the surface. The fish did
not seem as general rule to be
much alarmed. Once remember a
large red fish took the cartridge for
something good to eat and reached
it just in time to allow a small por-
ton Of his tail 20 reach the surface.
When the FIRE reached the fulmi-
nate Of mercury contained in the cap,
there would be q sudden white fash,
then quick, sharp detonstion, the
blow striking the bottom Of the skiG
as il some one had struck it with a
hammer; then, in 4 space of time
varying from eight to ten minutes,
every fish within a radius of forty or
flfty yards, would slowly come to the
surface. Those within the immediate
vicinity OF the explosion, Of course
were killed by bursting of the air
bladder, and injury to the large in