The Cleveland leader. [volume] (Cleveland [Ohio]) 1865-1865, 1865-08-09
new Insfruments,

I, New Instruments.
; The correspondent of the London Sta,
: gives q fuller account of the new electrica
4 i~nstruments in use on board the Great
Eastern:
Some Of the electrical instruments in use
on board are of great interest, though it i.
almost impossible to convey in any limited
space such an account of them as would be
comprehensive TO the ordinary reader
Three times q day has the cable been
tested for insulation and conductivity
by N. de Sauty, who is in charge of the
Telegrsphic Construction and Maintenance
Company, snd who has been present as
sisting or in charge at no fewer than
twenty-seven cables previously laid. Mr..
Cromwell F. Marley and Professor W.
Thompson, of Glasgow University, pro-
fessor of natural philosophy, represent the
electrical department of the Atlantic Ca
bic Company and, although it would be
idle to conceal that there is on many points
8 great divergence Of opinion among these
gentlemen, it says 8 good deal for their
u%sefulness that they work together willing
ly for the common objsct which mnst be
near the hearts of al them.
Some Of the instruments used are the
invention Of Professor Thomson; me-, the
curb key contributed, according TO his the
DRY, by Ar. Marley and himself being OF
peculiar delicscy and of much value. 1t
is a speaking instrument, arranged not
only 10 convey the messages, but to
govern and subdue the waves of the
electric current. It has been ascer-
tained-indeed the knowledge dates from
before the time of the last Atlantic
cable-that the electric current running
through q wire moves in fluctuations,
which must be diminished if the mes
sage through a long wire is 70 assume an
Ineligible shape at the distant end In
order to do this it has been found neces-
ssry 10 make each pulsstion st that end
the product of five distinct currents from
this end. Three of these are positive and
two negative the latter controlling and
reducing the undulstions of the former.
It is found by experiment that these five
produce only one spprecisble signal, the
rationale of which may be best demonstrst.
ed by calling the positive r (plus) currents,
and the negative - (minus) currents.
The two minus currents compensate for the
two plus currents, leaving one plus cur
rent TO go on unimpeded, or with only
such delay IS is due TO the natural resist
ance OF the wire.
To obtain these results the curb key is
moved by 8 treadle, which propels q gov
ernor of peculiar and delicate construction.
This governor, answering roughly to the
two balls on 8 steam engine, maintains q
perfectly regular speed, and acts on u shaft
furnished with two cams acting on TIVE
springs, which are alternately raised and
lowered as the fingers move the keys which
sh-F- 49, lssters according u the Morse
alphabet By the contact of the springs in
connection with the two cams the positive
and negative currents from a Daniel bat
terry are produced. IdonOt know if l have
is so delicate, though at the same time go
powerful, that have taken some pains 10
convey its leading features.
The Daniels battery above mentioned
will beln regular use, not perhaps that it
is more powerful, but that by it all risk of
spilling the acid is avoided. 1t consists of
g chamber in which is placed a copper
plate, over this being laid some sulphate
of copper (blue ~vitriol) Then is filed in
sSwdust, saturated with the proper proper
lions Of acid and water, and last Of an is
laid the zinc plste. The salt of copper is
reduced TO 3 metallic state, while She me
tsllic zinc is precipitsted in the form of q
salt; and the current is produced which,
when conveyed through the curb key pull
safes the message through the two thou
sand three hundred miles of wire in about
a quarter of a secondl Professor Thorn
son has also in use q delicate instrument for
sscertsining the amount Of electricity in
the atmosphere, and he also applies this
TO test the insulation of cables; but l should
fail in any respect to convey a comprehen-
sible description of this little instrument.
The code in use is that of Professor
Morse, adapted TO the SteinhiIl telegrspbic
system, and this for two reRsons-(a) the
Morse alphabet, one OF the most simple and
effective of telegraphic codes, and (b) it is
in general use on the American continent.
When the last cable was made, it was an
nounced that Mr.. Whitehouse was getting
seven words per minute through the whole
length. Sitting in his study in Glasgow,
Professor Thomson theoretically doubted
the fact; and on trial through the cable,
before the attempt TO lay il in 1857, the
result was that they could not be sure of
getting any signal at all through its whole
length. For the additional wire, required
for the 1858 expedition, Mr.. Thomssn's
theory was adopted, and this little acct
dent, it may almost be called, led TO his
prominent association with that cable and
the present expedition.
The instruments used on board for de.
termining temperature and the like were
some weeks ago placed in the hands of
Nessrs. Negrette and ZambrA for verihcs-
ton and adjustment and I believe they
have, up to the present time, given the
utmost satisfaction. The mirror instrument
used for receiving messages which pass
through the cable has been before the
public IN q shape not very different from
that BOW approved since 1868, and has
been 80 frequently described that l may
spare myself the labor and the Star the
space necessary to detail its features.