The Madisonian. [volume] (Washington City [i.e. Washington, D.C.]) 1837-1845, 1840-11-13
WHOLE NO. 4o6.


since that telegraph was laid down, Professor
Wheatstone and Mr.. Cooke have made con-
siderable improvements in the arrangement OF
the apparatus, by which all the communications
can be made by two wires instead Of five. The
simplifcation of the machinery must necessarily
diminish the expense, therefore II is not too
much TO expect that after more practical expert
ence the cost will not exceed one-quarter that OF
the first attempt. As the wires are conveyed
through water-tight tubes, rivers will form no
obstacle to the construction Of these telegraphs,
and Professor Wheatstone stated, in answer 10
a question from one of the committee, that he
conceived il would be perfectly practicable TO
communicate from Dover TO Calais in that way"
Notwithstanding all we have heard and seen
of this Electrical Telegraph, (says the Liver
pool Mercury we should prefer, for conve-
nience, simplicity, and cheapness, the mode Of
conveying communications through the pneu-
matte or atmospheric tubes which we recon-
mended in an editorial article, from which we
subjoin an extract:
although the process by which Mr.. Valance
proposed to propel carriages through his pneu-
matte tunnels is correct in principle and practi-
cable in application, there is no probability of
ever seeing il adopted on the scale contemplated
by the protector. The enormous expense of the
huge iron cylinders or tunnels, and the vast
number of them which would be necessary to
complete general or even an extensive line of
communication, preclude all rational expectation
of the adoption of such mode of conveying
passengers and merchandise Ii does not fol-
low, however, that the principle may not be sue
cessfully applied to the rapid conveyance Of let
tiers and intelligence, for which purpose it APP
pears to us to be peculiarly adapted, as il would
be more certain, more expeditions and economi-
cal than any other mode suggested whether
telegraphic, electromagnetic, or hydrostatic.-
When we use the term more expeditious,' we
do not, of course, mean that column Of air can
be propelled through a tube or tunnel with the
velocity Of light or electricity. We aware
that the motion of those agents is infinitely more
rapid than that Of atmospheric air, but we are
at the same time fully persuaded that pnuematic
tubes are much better adapted for the convey
ance of intelligence than the ordinary telegraph,
or than any other means which have been re-
commended for the purpose"
Photographic signals, whether like those in
ordinary use, or any other which have been sug-
gested, exhibit only word, figure or letter at
one operation, so that complete sentence can
only be conveyed as it were by successive in
stalments, whereas by the pneumatic apparatus
whole packet of letters would be despatched
with rapidity at one operation. In order to give
to the general reader correct notion of the
mcdus operdndi, we will suppose that between
Liverpool and Manchester, alongside the rail-
way, or in the middle Of the railway, small
tunnel were laid down, in which letter-box on
wheels should move on small railway the
tunnels of course, having exhausting pumps at
each end. Whom the letters had to be despatch
ed from Liverpool all that would be necessary TO
do would be to place the box or carriage on its
rail, and TO put the pump in motion at the Man
chester extremity of the cylinder, when the air
rushing in behind the carriage to supply the va
cum, would carry it forwards at speed pro-
portionate to the power Of the exhausting pro-
cess. We shall not hazard a conjecture as TO
the maximum velocity which might be attained
IN these pneumatic tubes; but we are thorough
ly convinced that the rate would be very rapid
even with a very moderate exhaustion. In the
experimental excursion made through Mr. Val
lance's tunnel at Brighton, the degree of ex-
haustion applied to produce considerable We
locity did not exceed the ten thousandth part of
perfect vacuum, which would not lower the
mercury in the barometer as much as the hum
dredth part Of an inch. We are indeed of OPT
Mon that greater velocity might be impaired
to the carriage than it could sustain, owing to
intense friction and consequent heat; but if it
be practicable TO construct carriage of materials
that would endure the friction occasioned by ex-
ccssive rapid motion, we see no reason why the
communication might not be effected between
Liverpool and Manchester in single minute"