New Orleans Republican. [volume] (New Orleans, La) 1867-1878, 1874-06-21
The TeredO.

| remedy the taking OF their deposition al
| the earliest practicable moment.
The TeredO.
The following essay, written by G. w. r.
| Bayley, Esq, of this city, was read at the
convention Of civil engineers, in New York,
on the eighteenth instant:
The object Of the writer in preparing this
paper is il possible, to add something to
what is generally known Of the habits and
operations of the teredo on timber struc-
lures, particularly in Southern waters on
the coast of the Gulf of Mexico. The libra
ries of New Orleans do not contain all of
the works of naturalists and others who
have written upon this subject, and circum-
stances have prevented the continuance of
the writer's observations respecting the
habits Of these ''borers of the sea-" and Of
experiments to ascertain and determine
the best means Of preventing their ravages
upon timber foundations under water
From Louis Figuier's ocean World" we
learn that the "Nollusca proper have been
divided by Cuvier into five sub.classes;
the first of these is called achphala.' To
this sub-class the ship worms belong. "They
have no head; the body is surrounded by
the folds of the mantle; the shell consists
Of two valves. Hence they are called bi.
valves, because their shell consists of two
halves. Although they have no head they
feed themselves and reproduce their kind.
The valves are united to the animal by the
insertion into them OF certain muscles, and
the mantle lobes stretch over to the edges
of the valves. The animal secretes calca-
reous matter and deposits it upon the ex.
IRENE edge of the shell, when the secretion
hardens and becomes converted into layer
of solid testaceous substance. Every new
IL formed layer enlarges the diameter
of the shell. The ship worm moves by
means of an extensive fleshy organ called
a foot. 1t is muscular mass. capable of
beng pushed out from between the
mantle lobes and the valves, and of adher-
ing by the exhaustion of the air and water
under 1t. to the front end of the tube the
teredo Is engaged in excavating or boring.
The writer is convinced that many species
are prOpagated and invade timber on the
coast OF the Gulf of Mexico, and that thew
vary very much in size, proportions and
markings, some of them being from half to
three-fourshs of an inch in diameter when
fully developed and from twelve to twenty
or more inches in length, while others are
much less in size. TryOn gives the dimen-
stems of the toredo norvagica Whose habi.
tat Is in the waters of the coasts of Europe,
Senegal, United States) as follows: Length
OF valves One-half inch, breadth somewhat
less; length OF tube about one foot, but in
some the tube is two and half feet.
The long bridges across Bay St. Louis,
lO,0o5 feet, and Bay Biloxi, 6l36 feet, built
on heavy yellow pine piles from fifteen to
and 1870, had to be reconstructed in the
winter and spring of 1871 by driving an
entire new set of piles in the place of those
destroyed by the teredo. The Bay St.
Louis bridge piles-the new ones-were
covered with felt aud copper, and the
Biloxi bridg piles with felt and zinc, from
the water line to the bottom, the depth of
Bay St. Louis being from ten to twelve
generally, and at Biloxi bay from ten to
fifteen feet. Before driving the new
piles the portion intended to include the
SIP ace from the water line to the bottom was
reduced to from ten to twelve inches in
diameter and rounded to receive the covering
OF felt and copper or yellow metal or felt
and zinc, which was put ON shore. At Bay
81. LOUIS the piles were not felted and cop
pered for sufficient length to allow for
the increase of depth due tolthe scosr caused
by the tidal currents and the contraction of
the waterway by the new piled butts. The
coppering reached the old bottom, but the |
bottom was washed out in many places |
around the piles in the new butts below the |
protectors, thus leaving them exposed to the |
ravages OF the teredo below. In 1872 the |
writer, who misplaced in charge of this road |
after the rebuilding of these two bridges |
across Bay st. Louis and Biloxi, EN-.
ployed diver, who used submarine ar.
NOR dress to examine such piles on both |
bridges. The examination showed that |
many OF the piles in the Bay St. Louis
bridge had been damaged by the teredo
below the coppering. To remedy the evil.
sand and clay were hauled in sufficient
quantities and dumped round the new niles
to cover the exposed posts, thus cutting off
Inc teredo's connection with the aerated |
salt water, and killing them in o few days.
The piles much injured were replaced with
new ones, previously charred, with coal oil
lar poured on them, washed with clear oil,
and coated with coal tar varnish, and ali
Dose or broken sheets of copper were re-.
nailed under water. 1t was estimated that
ms coppering, already considerably
mined by composition, was good for per-
1aps three or four years.
AS the teredo can not penetrate any soft.
lbrous or spOngy substance, as telling
NICK paper or the bark of pine timber. and |
MS Is the reason why the spongy, fibrous
wood OF the cabbage tree palm is never at
ac-ked by the teredO, the preservation of |
ne felt covering was certainly matter OF
'reat Importance. The action of salt water
lpon copper or zinc sheets is very destruc.
I've, and tarred felt is even better protec.
ion IMAM metal for submerged timber; with
METAL only, the sea water can penetrate
lnder the sheets, especially when loose or
'roken, and when sea water GIBBS and flows
With the tide, 80 can the ship worm enter
nd work. If felt, saturated with the dead
III OF coal tar, and well coated with thick
ned coal tar, can be secured to and main.
AIMED on the outside of submerged timber.
may be considered safe from the rayages
f the teredO.
The sap wood portion of yellow pine can
e easily charged with clear oil by boiling
an open tank with round sticks from
evenly to eighty feet in length; but the
ltchy heart wood can not be by any pro.
ess IN very large pieces, if at all. With
ound piles, unhewn, if the sap wood ia
hanged, and the cracks and checks are
lied with thickened coal tar no worms can
enetrate to the heart wood. It ia hettar
therefore,, to use round piles, and with the
ARK VI, on II not otherwise to be projected.
The ueredO works in our waters o. oil
epths, as at the bottom at PascaoonIa
earl river, the Rigolets, and Chef Men
eur. AT these places, too, where the denths
airy from twenty, to thirty, forty and fiftv
BET, the worm does not work near tha snv.
ace, Were the water ia fresh or brack;shs
ut beneath 1t. In some cases thew enter
lst ABOVE the bottom, and work their wav
Onward below it, as we'll az from mat
Glow the water line up. During our rsinv.
ammer seasons tho teredo does not appear