The daily exchange. [volume] (Baltimore, Md.) 1858-1861, 1858-06-24

fracture of the cable it was remarked with surprise
on board the Agamemnon that the rope had parted
in the machine instead of, has always been tho
case in submerging cables, at the last wheel going
out over the stern.
The second, third and fourth fractures also talk
ing place between the wheels of the paving out ap-
paratus and in precisely the spot as the first
break, endeayors were made to account for these
unpleasant condolences. The was soon ascer-
tanned In the process of paying-out the cable .
passes over two large Wheels each of which has
four very deep shaped grooves. Before the pres
ent improved paying-out apparatus was designed. |
the great difficulty in sinking cables had been their
liability to surge when an attempt was made to |
check their spced-that is, the rope slipped over
the wheels without turning them. In the present |
machine, to obviate this serious danger each ofthe
eight grooves in the wheels was made with rcgu-
larry increasing circumference of oneeighth of an
inch, so that the slack rope if any, would be alb
sorbed entirely in the continued stretching the
rope underwent in passing round.
Apparently the increase of circumference was so
trillng as to be of no importance either way
the other, but moments reflection shows that, in
reality, it effected such change in the condition
of the rope would render it little short of i'm
possibility to submerge it without breaking. The
increase OF one eighth Of an inch in each groove
stretched the piece inch and Oneeighth in pass
ing through the machine
The whole length of the wire in the machine
Mt time is 100 feet but 80 feet makes complete
circumference of the two groovcd wheels, and of
course as there could be no surging slipping
back. it amounted to stretch of one inch and one
feet entering on the small diameter of the wheel,
passed oil at the large end and therefore every so
feet, so to speak, event through the mill, and
was stretched to its gradually increasing diameter
coming out at last 80 feet IS inch long.
If the whole length Of cable was thus paid out
it would stretch it some ii miles longer than it is
now A weight of one ton suspended to 60 feet of
the wire stretches it one inch, but it would require
nearly three tons to stretch 80 feet IS inch longer
| What made this strain the worse that it was
one of which the dynamomcter indicated but small
| share Therefore, when the cable broke between
| the wheels, with the dynamometcr standing at a
certain strain, it only gave the amount of force
qured to overcome the resistance of the machinery
and brakes, with the addition of the strain exertcd
at powerful leverage to stretch the wire between
| the wheels.
| In truth, therefore, there is no knowing the
| actual weight at which the coil broke, and it
can only be presumed that as the Company have
made many hundreds of experiments on its
strength, and have never yet met even with faulty
! piece which broke at less than four tons, while
| very many of them have stood as high as eight,
| none of the ropes broken during the experimental
! trip gave way at lower strain than the lowest
have mentioned Directly the trip was OVER and the
| wire squadron anchored in the Sound, there was
general meeting of all the engineers and others in
charge of the machinery on board both the Agamem-
non and Niagara, and whatever doubts remained as
to the risk incurred by the increasing diamcters of
the wheel grooves were at done away with
| when it was found that the Niagaras cable had on
all occasions also broken in the machine, and at
| precisely the same spot as the same accident oc-
| CURED on the English vessel. This was regarded
as conclusive, and accordingly it was resolved to
! land the wheels at keyham, and have all the grooves
plancd down to the same dameters, which was done
| forthwith.
Mr. Amos and Mr. Appod objected to this opera
ton as unnecessary nasmuch the wire was not
stretched inch in 30 feet, but only inch in 100,
and that in fact the stretching required to pre-
vent the coil surging or paying back. At the same
time, however, they distinctly expressed their opn-
ion that though unnecessary the planning down
! would do no harm. There can be no manner of
doubt but that this alteration is most important
! and valuable Improvement. There is not the least
possibility Of the cable surgng, as the tar prevents
| it. When the action of the machinery reversed
for hauling in, of course the cable wound in at
the largest wheel and off at the smallest, and the
cable, if ever, would have surged then, but never
did, though the strain at time was at its hghes
point.
ara the experiment was perfect. At time did
the dynamometer indicate higher strain upon the
wire than 81 cwt.-about cwt. less than that on
board the Agamemnon. The greatest speed at
which the coil was ruT out, at the rate of 100
iathoms in GA seconds, or rather less than six
nautical miles hour; about the same within
few tathomsl of the greatest speed Of the Aga
The. Niagara not only cast loose her large buoy
and bhoycd four miles of cable but she also attach
ed one of h,r small buoys at about mile from the
largest. Both answered the purpose in every re-
1 spect. Shortly after buoying with the smallest the
coil parted from the Niagara, and the sudden Jerk
caused it to break away from both the buovs in
precisely the same manner as it occurred with the
Agamemnon's wire.
An examination into the cause of this showed at
once that the tastenings used to the cable to
the buoys were not sufficient either in grip or
| strength IN case OF any sudden pull. These have
accordingly been altered, and made capable of en-
during ten times the strain the wire can ever put
on them The form of the splice also has been
slightly modified, from semi-circle to Il slight
scdgment of n circle and by this the chance of the
wire untwistne in its descent is still further guard
ed against.
Thus, every precaution which skill and foresight
aided by practical experience, suggest. has been
adopted, and all the apparatus may be regard
ed as perfect Some donbt still exists whether the
Agamemnon will sail be towed to her destination
in mid ocean. Captain Hudson, of the Niagara is
determined on steaming; but the Agamemnon is
already so full that it is no longer doubtful that
she cannot take the Goals necessary for eighteen
days steaming: Though the sacks slowed in
temporary bunkers along the main deck it has not
been found possible to cram more into he than 4SC
tons, or, at the most extreme computation, only
coal for fifteen DAYS.
Under the most favorable circumstances this is
the time she must occupy in the VOYAGE but if even
Il single day were lost in making the splice she
would be unable to steam at the most critical part
of the voyage. namely, when approaching the coast
of Ireland How this difficulty is to be got over is
not yet decided. though most probably it will be
arranged by giving the Agamemnon, towed by the
Nalorous, couple Of days start of the Niagara
This would do all that is wanted.
= vessel beer
dispatched to newfoundland. She will wait fo1
the Niagara at Trinity Bay, and pilot her carefully
through its intricate navigation to the Bay Of
Bulls, where, if all goes WELL the wire will be
landed, and the latest advices from New York anC
Washington instantly transmitted. During the
paying out no messages are to be sent through the
wire from ship to ship. but merely constant cur
rents, TO show that the insulation and electrical
continuity perfect.
The rendezvous in mid ocean for which the
squadron steers on leaving is 81 2 north latitude
$50 lS' west longitude. Where the American side
of the cable will be landed is in 40 49, north 90
west, and the tclegraph-house at Nalenta is in 81
;; So north, 100 % west The precise distance be
! tween the two points is l,720 nautical miles The
length of wire in both vessels amounts to 29Gt
nautical miles, that there is at least so or %
per cent. allowed for slack and contingencies
In our account of the experiment trip we stated
that Mr.. WoOdh0use went on board the Niagara
, as electrician. This a mistake. Mr.. Wood
f house went as experimenting engineer, and Pro
, lessor WhitehOuse was electrician
5 DEPARTURE OF THE FLEET
PLYMOUTH SOUND, June TO-
4 sudden fit of energy the part of the author
tiles at this port has decided that the squadron is tC
go to sea without further waste of time When we
informed our readers, yesterday, that each vessel
was ready to go off at moments notice. we did Sc
2 under the firm impression that steamer was an
pointed to tow the AgamemnOn to the rendezvous
in mid-ocean. At the last moment, however, it ha
been decided that she is to sail there in spite of the
D fact that she is iury-rgged with 4O-Gunfriga +,
mass, and deep in the water that she will scarce
ly move to anything short of half gale.
= When to these drawbacks is added the important
fact that light westerly winds always prevail at this
season of the year, readers will easily be able tc
estimate the time which the English portion of the
expedition is likely to occupy in reaching tn,
centre of the Atlantic. The Vaorous, a Steam
trigate capable of towing two vessels lik,
the Agamemnon, is to go with her, but OF
: no account, to tow her, and in case of hel
being tempted in any sudden emergency to infringe
TINS rule she is only supplied with Goals enough tc
take herself back to England after sailing to the
rendezvous. 1t may, and very likely WILL be urged
that the Nalorous had not enough Goals on board
to tow the ship, but at least it cannot be denied that
the Gladiator, frigate capable of towing the Aga
memnon half round the world, is left behind idle
4 hnr rnnn rinnnrs hnrn Irn,,. - :. IL