The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1898-12-20

Joseph Letter Explains How Com
pressed Air Is Applied.


The proposal to use compressed air as a
means for propelling street cars and other
vehicles. as contemplated by the Interna-
tional Air Power Company, of which Joseph
Letter recently secured control, has Sug-
gested to the minds of many people ques-
tons as to how the air is compressed and
how it is applied in moving a vehicle. And
among the queStionerS are not lacking those
who doubt If the problem on which invent
ors have spent much thought and money
during the last few years at last has been
solved in a practical way. Mr.. Letter be-
lieves it has. His investment is sufficient
proof of this, and to show that he has rea-
son for the faith that is In him Mr.. Letter
yesterday afternoon explained the methods
by which the new power is created and APP
Piled and the manner in which they differ
from those marking former attempts 70
make practical use of compressed air as
power all of which have failed.
1T cannot be said any longer" said MIR.
Letter, that this new system of using COM
pressed air as power Is an experiment 1t
has been thoroughly tested on the Metro
politan Traction Company's line in One-hun-
dred-and-fifteenth street New York city,
and result that company is installing
plant for the use of air power on it's lines
on Twenty-eighth, Twenty ninth and Thir-
ty-fourth streets. The compressor plant is
being built at TWenty-fourth street and the
East river. After all, the whole method is
rather simple Air IS compressed in much
the same way as has been done by other
companies that have tried to make practical
use of air power and have failed. The
trouble has been In every case that the in
Ventors went so far as to create the power
all right, but did not have good mechanical
engineers to aid them in applying that pow
er. That is their motors were defective. 1t
is in that particular the International Air
Power Company's system and that of the
American Air Power Company, which has
the patent for this country, excel.
Now to begin at the beginning. The
air is compressed in cylinders, arranged in
multiple series. In the first cylinder the
air is reduced till it gives a pressure of six
ty pounds to the square inch against the
atmosphere, which itself has a pressure of
thirty-twO pounds to the square inch against
a vacuum Then the air is reduced in a
second cylinder eight times, that is, till its
compass is one-eighth what Ii was in the
as great or $50 pounds TO the square inch.
The same multiple is preserved in the next
compression. so that in the third cylinder
in the compressor plant the air has pres
sure of $40 pounds to a square inch.
This high pressure air is kept in a tank
and when wanted for use on street cars
to run their motors is drawn off into what
we call bottles These bottles are connected
in series. They are cold punched nickel
steel and of great strength, for they sustain
a pressure of about $500 pounds TO the
square inch when placed on the car
From this IL is not to be concluded that
the pressure in the motor cylinder when the
car starts Is a pressure of $500 pounds.
There is where our motors differ from their
predecessors The outfowing of the air
from the bottles is controlled by system
of reduction valves, which deliver the air
into the cylinders at a pressure of 125 pounds
to the square inch. Engines can be made