The Express.
London, England, 1858-09-27 00:00:00

THE ATLANTIC TELEGRAPH.

(TROY a 00112SPONDINT.)
VALENTIA, FRIDAY, 81PT. 24.
Since my last communication no improvement has
taken place is the electrical condition of the At-
lantic sable ; nor, indeed, until within the Mit few
days have any operations or experiment, (beyond
those the results of which have already been com-
municated) been undertaken to ascertain the nature
of the leakage in the cable, or the probability of
working through it in its present condition. Up to
yesterday everything remained instals quo. During
leach alternate hour the regular succession of signals
previously alluded to are despatched, and during the
intervals the galvanometers of Professor Thomson are
watched formome indications of current. from the other
side ; bat these, v nfortunately, ars seldom sees at all,
and stillmore rarely can these slight deflecations be
depended an as currents from Newfoundland. How-
ever, there is still this much cause for satisfaction,
that the fault does not get worse at any time, while
it occasionally, for a time, improves. Considerable
and distinct " reversals" from Newfoundland are
discernible. The opinion prevalent among many
here, that the principal fault in the cable is com-
paratively near shore, daily gains ground, and though
Professor 1110M/01:61 opinion is directly opposed to
such • supposition, I cannot help thinking that
there really is mere in it than was at first sup-
posed. For the reasons given in my last letter
there is no doubt a fault existing in the cable upon
the bank which divides the shoal water from tho
depths of the Atlantic, about 220 miles from the Irish
coast. Bat this faalt, witheat the existents at seve-
ral minor faults nearer shore, would not nommat for
the total interruption of the currents sent from
either termini. All that Professor Thomson, Mr.
Henley, or Mr. Varley can say respecting the fault
is that it gives a resistance to the electric current
equal to 300 miles of the cable. Not it does
not therefore follow that the interruption is 300
miles away, for by passing the oarrent through
a few yards of fine wire in a basin of salt water, the
very ease amount of resistance can be produced.
Though the distant fault may tend to interrupt the
small portion of the electrical current which passes
the nearer faults, yet, if these more accessible ones
were repaired, it is the opinion of many here com-
petent to judge of the matter that the supposed
lose of insulation out at sea would not ma-
terially affect the working of the lies. The
more recent advice. from Newfoundland de- ,
cidsdly tend to strengthen the opinion that
the main interruption is close to this place. Mr.
Cyrus Field, in writing from America, says that " no
messages have been received from Ireland since the
let instant, though the iusulation of the cable re-
mained perfect." Now, according to the experi-
ments of Professor Thomson and ethers, it has been
ascertained that a loss of insulation 300 miles from
either shore would effect the currents sent from
both ends equally, whereas if the defect were close
to either station, the loss of insulation would only
be apparent at the termination nearest to it.
A very similar defect so the present occurred
• short time ago in one of the North Sea cabin.
Mr. Farley and other scientific gentlemen tested the