New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1897-04-11
K VI. N Z NVlSIi a|SSlyyDNIV W
THE CARRIER.


the latter to extend It eventually to the trans
portaton Of general merchandise also.
The distinctive features Of the modern pneu-
matte method of transportation will appear more
clearly after a short review Of what has been
done in the past. Although something Of this
sort suggested 10 the Royal Society in Lon
don more than two centuries ago. 1t not
until 1881 that the notion reduced TO
practical basis An electric telegraph company
In the British capital laid an acknowledgements
tube between its main Office and a sub-station
ESQ feet distant. for the purpose Of sending writ
ten messages TO the latter point. 1t found
that these could be distributed more quickly in
this manner than if they were repeated over
wire or sent in budgets by a messenger. The
messages were rolled up and placed in small
cylindrical boxes made of gutta rcrcha and
drawn through the tube by suction. In spite of
various mishaps the plan possessed enough
merit to prove successful. The pneumatic tube
system Of London has now developed TO de-
gree where thirty-four miles of tube serving
forty-two stations. are required.
At first only a single tube used. but af
terward TWO tubes were employed, on, TO take
boxes each way. Propulsion was also effected
by forcing air into tube behind a box. instead
OF resorting 10 suction. One Of the advantages
OF this method is that II several boxes are dis
patched in rapid succession they will not over
take one another and lodge al some intermediate
point as they do when suction IS resorted 10.
For convenience, however ii is common to-day
70 operate small tubes, which are not called upon
10 perform frequent service by suction to carry
messages In one direction and by pressure 10 carry
them In the other. The operator tube clerk"
a. one end of the route, by merely pulling
lever. can reverse the direction Of the air cur
rent Telegraphic signals from the other end OF
the line indicate when II is desirable to sub
stl.ute suction for pressure. 1t thus becomes
feasible TO get along with single tube. Blu.
where business is done on a large scale 1t Is
customary TO have a double tube. and rely ex-
clusively upon pressure as the motive force.
The size OF the tubes and the method of unit
Ing the sections composing them have under
gone great changes in the last forty years
Many OF those IN service in London. Paris and
Berlin are two and one-haf or three inches In
diameter Those operated in Philadelphia dur
ing the last four years are six inches through
That which will connect the New-York and
Brooklyn postoffices and which VIII reach across
the East River Bridge viii be an esht-inch
pipe The Tubular Dispatch Company VIII use
eight-lnch and ten-inch pipes in New-York city
Brass cast-iron. wrought-iron and lead nave
all been used TO make these tubes. 1t is neces-
sary 10 exclude moisture from these conduits,
and. therefore. the joints must be water-tght
In London, for a time, a lead-hned IRON pipe
was employed and it was found necessary 10
solder the lead In making the connections III
order TO preserve the circular cross-sectioh our
ing this operation a mandril, or round IRON
rod, was inserted temporarily Aferward cast
iron pipes having turned-up fanges al the ehds
and fastened together with bolts were trled WIFE
excellent results, but packing was required ~
the joints In Philadelphia a cast-iron pipe
with be-9haped enlargement at one end IKE
that gas main. is employed. The JOINT Is
filled with molten lead. IT is believed that th~
effects Of contraction and expansion resulting
from temperature changes are met In TINS way
better than In any other. and this style or JOINT
also admits OF making slight curves in the line
without bending the pipe itself.
In Of the earlier plants the suction or
pressure was applied only at intervals. and when
occasion arose. There large stout metal
tanks, into which compressed air had been
forced. or In which ION the other hand a vacuum
had been created by exhaisting the contents
1t was only necessary. therefore, TO open a valve
u order to establish connection with the trans
mission tubes This was a convenient way or
peoring power. and promoted economy In its use