San Antonio daily light. [volume] (San Antonio, Tex.) 1886-1907, 1890-08-27
AIR AS MOTIVE POWER.
USE OF THE PNEUMATIC TUBE IN
THE POSTAL SERVICE.

A Proposition to Introduce a Quicker
Means of Transportation Serious
Obstacle Is the Great Waste of Energy
in Transmission.
A great deal of surmise and comment is
taking place in engineering circles about
Postmaster Van Colts remark that the
only solution Of the problem of the rapid
collection and distribution of mails lies in
the adoption of the compressed air system.
A correspondent thinks that this system
could also be adopted with advantage for
the transmission of samples, packages, etc,
which are frequently subjected to many
delays with the present express facilities.
Some officials seem to regard such articles
as of little Importance, whereas it is often
of great moment TO have samples forward
ed with all possible dispatch.
The possibilities of compressed air are
as yet not fully realized in this country
The pneumatic tube system of communi
cation is of course in use in many of the
big down town stores, in newspaper of
fees and to some extent between Western
Union offices; but there exists great deal
air, even among engineering experts. OF
course the principle of the system is well
understood, but except for mining opera
tions and for sending articles from one
part of a building to another it is not in
general commercial use in the United
States.
A leading engineer said to reporter the
other day: This compressed air system, OF
which there is so much talk, is financially
well supported, but it's all humbug" This
expresses the opinion of great many who
are supposed to be thoroughly acquainted
with the most recent developments of me
chanical science. But as many whose oc-
cupation does not lead them to make strict
investigation into the feasibility of all the
mechanical cOntrivances that come into
public discussion are beginning to think
that the use of compressed air would solve
many postal difficulties and also mitigate
the smoke nuisance, brief summary OF
the information on the subject Is given
here.
THE SYSTEM USED IN PARIS.
1t is generally believed that the system,
now in actual Use in Paris, has solved the
question of the speedy transmission of let
tiers ard parcels. But this system was
first adopted for the purpose of regulating
the clocks of the city on the pneumatic
button principle, to obtain a uniformity of
time all over Paris. A large number of
capitalists became interested in the scheme,
the company extended its operations and
the principal business of the company at
present is tag supplying of power to manu-
factories in different parts of the city.
The power is transmitted from the works
which are situated just outside the city
limits, in pipes through the city sewers
One advantage of this system is that there
is no escape of steam in the factories where
it is employed, and it does not vitiate the
atmosphere in which the workmen spend
so much of their lives In fact, the escape
of air into the rooms is beneficial, as it
helps to cool and ventilate them.
On the other hand, the fact that up to
the present time it has been found impos-
sible to devise any means which would en-.
tirely obviate the continual leakage of air
makes the commercial utility of the sys-
TEN doubtful. 1t has been found that in
transmitting air for mining purposes sc
per cent. of the power is lost. OF course
in transmitting the air to great distances
through the qualifications of a vast city
the loss of power by expansion is vastly
greater. 1t is possible that the percentage
of waste allowed by the company in Paris
would brighten American capitalists, and
make the adoption of the system here com.
mercially impracticable. Indeed the sys.
tenn in Paris, although Endorsed by gener.
Gus capital is still in an experimental
stage.
TRANSMISSION OF LETTERS.
The system has conclusiveiy proved that
the scheme is quite practicable physically,
although the inevitable waste of power is
Numerically opposed to the generally &C.
cepted ideas of mechanical economics.
Such a service is practicable if the public
can afford TO pay for it at such rate as
will insure revenue sufficient to cover the
loss of power. But that loss of power
makes all the difference between profit and
loss, and it is entirely possible that in New
York at leaI. compressed air will never be
come serious rival to electricity.
The pressure kept up throughout the
system varies from seventy-flve to eighty
pounds, sufficient to tear letters or pack
ages all to tatters. 1t is strange that the
transmission of letters should not have at
tracted the attention of the company if it
could be done protitably, as for this pur
pose about three pounds or four pounds
pressure is amply sufficient. And the fact
that they have not made use of what seems
such an advantageous system is an argu.
ment in favor of the statement that the
service the public demands must be so
cheap that this system could not fill the re-
quirements without a financial loss.
There are, however, other uses to which
ingenuity is beginning to apply
air. 1t is rumored in Paris
that company will shortly supply COM
dressed air ut such n low Temperature that