New-York daily tribune. [volume] (New-York [N.Y.]) 1842-1866, 1857-08-29
Of the body to be moved and the velocity to which


il is to be brought are known, the exact quantity Of
power necessary to bring the body from rect to
the given velocity may be exactly calculated.
But given quantity Of power may be applied 10
various ways. For example a work equal to rails
ing twelve pounds one foot may be produced By ap'
plying one pound moviDg distance Of twelve feet,
or BY four pounds for three feet or twelve pounds
for one foot, or one hundred aud twenty pounds
for one tenth of foot And if this pc yer is trans
mitted to or from a body through cofd, this cord
will have to bear strain Of one, four, twelve OF
one hundred and twenty pounds, according 70 tue
manner Of Transmission. This force is in 40 IN
verse ratio to the time-thsti is to say if quantity
of power is transmitted to body BY exerting on IL
force of two pounds during one second, the same
power will be transmitted to it by strain of one
pour during two seconds. AT the end OF eotn OPP
erstiops the body would have attained exactly tue
sane velocity.
The case of the Telegraph cable is similar to
that of the weight suspended by Irvine, in our
experiment The part of the cable just outside
tia stern of the vessel is the counterpart OF the
msptnding twlne; the two miles of cable hanging
above tne DOttoul represents enO "oi6"s' ""N -
pitching and raising Of the vessels stern gives the
Jerk. The cable is capable of carrying six miles OF
its weight in water. When broken, it had to carry
| two mes-tbat is, one-third of its suspensory ca
| pacity. AT the time of the rupture, the wind was
south. The swelffs heavier with this wind than with
any other in the open parts of the Atlantic, where
the vessels were and it ia very moderate estimate
Al e kbo N.sna yuan
| feet and rose tel feet every five seconds. rms
gives to the jerk velocity of eight feet second ct
the maximum point. This was quite enough TO
break the cable; but it was not all. The cable
being in the water exerted on it friction which
lie not much at the surface, but which may be very
great below. If the law of friction for solid and
fabricated substances, namely. that it is proper
tiorate to pressure, hold true for water, this
friction has 10 be overcome whenever the
cable is pulled up. The surface of the cable is
not even, and the water lodges itself in the
twist This water is put in motion as the cable is
pulled up, and its momentum must be overcome.
Thus not only the inertia Of the cable, but these
Last causes also would of themselves be sufficient to
break the cable on lite being stopped by the brakes
and pulled up BY the motion of the vessel. AT the
same time as long as the cable is allowed to run
out freely these same causes act in contrary man
ner and are great help to the work. The resist
ance of water and its friction retard the sinking and
sustain the cable go that if does not drag too heavily
For this reason if there were an indefinite supply Of
cable on board, and if the sinking few Thousand
miles, more or less, were of no consequence, the
plan taking off the brakes reducing the number Of
pueys in the paying out machinery, and starting
at full speed across the ocean, would undoubtedly
succeed. But as the supply of cable is limited, it
is necessary to have the means of regulating the
quantity padOut, and also to stop it altogether for
the joining Of the two parts in mid ocean.
Having thus made plain the cause of the present
disastrous failure, it remains to speak Of the means
of absolutely avoiding its repetiti IN. This will,
perhaps, be best understood by recurring to
Illustration of weight suspended by Irvine. At
tach the Irvine to the extremity of a coil.sprng of
thin wire say three feet long, and capable of play
ing one foot without much variation, and let the
other extremity of this spring be held in
the hand If sudden jerk upward Of half
foot be given, as in the frs. case,
the suspended weight will for a moment have 40
apparent motion, and then it will slowly rise half
foot. If sudden jerk down immediately followed
by jerk upward in rapid succession be given by
the hand, the weight will not move from its place,
but slight vibration of an inch or two will be the
only result, and all the time the strain on the sus-
pending Irvine has been equal to that on the spring
that is, very little over the actual weight o tho sus
pended body. This experiment will appear yet
more conclusive by suspendpg twelve pounds
instead Of one. A similar arrangement should be
adopted on board the Niagara before the cable can
be sunk. A primitive way of carrying this idea
into practice, (mentioned here only to make the
explanation clearer consists in hanging large
puly % feet above deck from the top of the mast,
by means Of a strong elastic strip of Iudia rubber.
This rubber should be strong enough to bcsr three
tors and when pulleduponb threeaud half tons to
play twenty feet, thus letting the puly come down
within five feet Of the deck. The cable from the
paying-out machinery would go up, pass over the
suspended pulley, come down, and thence over
another pulley into the 1t is obvious that with
this arrangement the pitching of tho vessel would
leave the sinking portion of the cable undistdrbed,
but would simply cause the suspended pulley to
play up and down. 1t is also clear that the increase
or decrease Of tension of the cable will be made
visible by the motion Of the pulley, which will in
dictate that the cable should be let out faster or
slower. To be complete and practically successful,
the elastic attachment should have more than twenty
feet play. We have thus far spoken Of an India.
rubber spring, for greater facility of explanation;
but the best arrangement probably would be springs
of sir or steam, built cOmpacty on deck, or be-