The San Francisco call., 1904-03-20


New York and Chicago will be con-
nsctsd by an eight-inch pneumatic tube
II present plans Of capitalists and com
pressed afr engineers are realized. The
scheme is declared TO be practical and
the odd feature OF the proposition is
that the projectors are not looking to
Uncle Sam for a subsidy or the United
States mails as the principal source Of
revenue. 1t is figured out that the net
income from the transmission of light
packages between the terminals and
intermediate stations viii be sufficient
to pay good dividends on the invest
ment. The success Of the pneumatic
tube systems for the transmission Of
mail matter in New York, Boston and
Philadelphia and the dispatch Of mes
sages in London, Paris, Berlin, Vienna
and Brussels is cited to prove the prac-
ticability and actual economy of COM
pressed air as carrying agent Chi
cago is to be equipped with pneumatic
tubes for the use Of its postoffices, and
pneumatic engineers look forward to an
early day when all the large cities of
the country viii use the swift service
and packages.
The projectors Of the New York-Chi-
cago pneumatic tube system are not
figuring on any 100 mile-an-hOur ser
vice They say a speed of forty or
fifty miles an hour viii be sufficient 10
meet business needs, and claim there
will be no trouble tc maintain an un-
interrupted service. Nor is it their pur-
pose to run bee line between the ter
minsl cities so as TO provide the short
est way for the steel carriers TO
travel through the cast-iron pipes.
The scheme contemplates a route
which will take in as many large CEN
ters Of population as possible without
straying too far from a practical di
rect line. This route would follow the
Hudson River and Erie canal to Buffa-
10, and parallel the Lake Shore road
70 Chicago. Every city of any consid-
cradle population On the line would be
an intermediate station, with relays
and power plants at necessary points
At first blush it would seem that this
proposition TO Ill an eight-inch pipe
with air al a pressure of twenty-five
pounds more or less to the square inch.
the said pipe reaching from Chicago
TO salt water. was che of those vision
airy schemes which pop up every week
or so. But these are days Of big things,
and the building Of a compressed air
pipe line between Chicago and New
York would be but the extension Of a
system already in operation. Pneu-
matte engineers assert there is nothing
mechanically or constructively against
the proposition; it all comes down to
the matter Of money.
Those who look upon pneumatic
tubes and the employment of COM
pressed air to carry cylindrical boxes
through pipes as something very mod
ern will be surprised to learn that half
a century ago a pneumatic tube was
put in operation in London for dis
patching kilograms It was only an
inch and a quarter pipe, 700 feet long,
but IL worked so well that a few years
later another tube two and a quarter
inches in diameter and over 5000 feet
long was laid down. From this begin
ming sprang LOndon's present network
OF tubes, which covers the business
part Of the metropolis, connecting the
general postoffice with all the subpost-
Offices. Berlin has over forty miles of
the European system are of small
diameter. none exceeding three inches.
This limits them TO the transmission Of
kilograms and messages. In many
American cities small sized tubes have
been used for many years for carrying
messages; newspapers have used them
for the transmission Of press kilograms.
Il,
stall q pneumatic tube system for car
rying the mails was successfully made
in Philadelphia in 1892, the tubes being
six and one-eight inches inside diane
ter. Boston and New York followed
with eight-inch pipes. Thus the Post
Office Department set the example,
which is certain TO be followed by the
commercial world.
The boy who uses a putty blower
illustrates the principle on which the
pneumatic tube system operates The
boy expels ai- with puf-the air car
ries with il the ball Of putty. The air
actually flows through the pneumatic
tube II is not "puffed" through how
ever, but is forced through the pipe.
The tubular steel carrier, slightly
smaller than the inside diameter Of the
tube, is carried along by the air cur
rent until il reaches the point of deliv-
cry. An air compressor forces the pipe
and the same air current brings the
carrier back TO its original starting
point through the return tube.
The tubes are cast-iron pipes, closely
resembling water or gas pipes, but the
shell is thicker and the quality OF iron
is better Each twelve-foot length of
pipe is bored to a true cylinder and
particular care is taken to make all
joints air tight. For short bends seam
less brass tubing is used somewhat
larger in bore than the cast-iron pipe.
for allowance must be made for clear
ance so that the carriers will not stick
while shooting around bend.
The carriers are made Of thin steel
They are cylinders closed at one end