New-York daily tribune., 1861-08-11

The PSEuMArre DrsPATcH TUBr.-The passen-
GERS by Citizen stsmboa, TO Chelsea may oeferye on
the open quay whjsh adoins the premises OF tne
Southwark aud yar,xtall Waerworks, near ba'sefses
pier long range Of black iron tubing, half sunk 10
the earth and extending distance OF about 4o yards'
along the brink Of the river, except where &s9
windnr turn and dives under ground before entering
she'd This tube is the object OF certain experiments
which began on Tuesday, aud Will ee continued for
a few DAYS. The transmission Of packages BY pneu-
matte pressure is not idea, In practice is IL
without an example, for the Electric Telegraph Com
pany have for period Of Elk yesrs, employed the
same means in collecting their messages fOm districts
Immediately surrounding their chief station. But the
clan on which the Pneumatic DISPATCH Company IND
lend with the aid of their engineers, Msssss. 7. W.
Ramnell and Latimer Clark, 70 apply the principle
more widely, embraces two or thea novel rointe
OF mechans. The tube which lave Ia; .:.Jie, 4
about thirty inches In diameter Ii has rails, which
are sodly cast within it, The which are 70 bear
the dispatches and mail bags also OF cast iron, with
wheels which the rs; but the cars themselves
though corresponding In shape with their receptacle
vacuum or complete exhaustion Of atmosphere 10, in
fact required. The failure of the old stmosE hcrc rail-
way was attributable partly the enormous pressure
aud partly to the necessity OF opening and closing con-
tnuous valves often as train was sfartei Neither
difficulty with reg srd TO the Pneumatic dspateh
tube The pressure IN this case Is about Elk inches OF
water which does No. equal half the vaiiaion OF e
barometer. A maximaln speed OF Twenty-Five miles
hour may, We believe, De attaineui OUT hH, ~ wen
as the weight Of the carriages and their eoutenis uet
be question Of mechanical power. A 70 distxnee,
there is a more decfied limitation; and we doubt
whether the plan would work beyond length OF Eve
miles. Il viii be for in crowded towns that
the pneumatic dispatch tube will prove Q
boon; and It's fret operations In London VIII
probably be in connection with the General Pcef-
Office The machinery by which partial exhaustion
of air within the tube Is effected may be briefly de-
scrbed In the shed TO which we have alluded l. an
engine which works directly by crank on the AIR OF
a eouple of discs, the diameter Of which n n feets
There ID space between these discs, not WIDER tnao
three or four inches at the edge, but greatly
toward the CENTER where . barge body Of sf Is ned.
BY the rapid and simultaneous revolution OF tnese
discs, the air is expelled at the open ndes ns ~
mupcates with the tube, certain quantity q af
is abstracted and corresponding pressure o. eoaise
takes place, by which the motion Of tbs esS
il governed On their approach 70 tns enc %
their Journey q check Is given 70 Their spSsa
by a very Ingenious arrangement. -1bc exnauIn9
n.aeh,nery. instead of acting on the whole Sngsh~
the tuhe. communicates with 1t By brancs RaPe.
some litte distance from the end AS soon ~ ,ns -
riages have passed this pipe, they are no ion ~.
iecf 20 the came motive iaiuenoe, ana sss ~ ~. 80,
vance of hem acts as kind Of natural o9nsI sssTI
,a';n. forcs Of which eau again be regulated y VII
by ,he attendants who hear the srproacn'ne u~
there IL really no saying that this m,chney .scirs
ssrve tbe purpose of aways a. well % tpe re9sh hs
rnenss of the Poet Office, and that we nay - - .ns
blown through q subtensneous Pea-shovssa, S.it,n9
end of London TO the other. Let ~ w -srsSysS
for this more remote benefit, ecugfa1Sa, Sa,,ss;ss sod
on the near prospect OF increased Ios. 80 sreW1sd
diminished traaic through our aAsssS ~
Streets vi yst8es1 q -