The Providence news. (Providence [R.I.]) 1891-1906, 1898-06-25
PNEUMATIC
TRACTION
Details of the Plan For
Its Operation.
ENGINE OF HIGH POWER.
Th. Largest Installation Of lis Kind
In America.
FUTURE OF COMPRESSED AIR.

VAASA AAoy PAosO . "a 'ADV
the general public interest In urban
traction.
To beeNi with, the COMPRISING ma
chine will DO q monster, by far the lar
gest In the United States, and noc much II
at all inferior to the oompressors used to
pack away atmosphere for the propulsion
of street cars In Paris. The steam engine,
forming part of the compressor, will be Of
/ 200 horsepower when running on 100
pounds Of steam at 40 revolutions q min
ute. Its power may be largely increased,
since 1t Is being built to make 70 revolu-
lions II necessary. Those who understand
something of steam engineering will DO
interested in knowing that 1t will be Of
the compound type, with vertical cylin-
ders Of go inch stroke. The big hywheel
will be 20 feet In diameter and Its weight
will DO 62H tons, or rethcr more than
the average locomotive. The valves will
be of tho Corliss cut of type. The air
pumping cylinders will be four In num-
Der and at each revolution of the engine
they will deliver 80 cubic feet of air crowd
cd down to the enormous pressure OF z, 800
pounds to the square inch, about 30 times
the ordinary steam pressure maintained
in . locomotive boiler.
An Expensive Experiment.
The friends of compressed air under
stand full well that the installation Of this
plant and the use of their favorito motor
power on one Of the cross town lines will
be really nothing more than an expert
ment. Yet, as 1t will cost 800, 900 or
more to try 1t and the bills will be paid by
the enormously wealthy Metropolitan
Traction company, they feel sure its trial
will be fair and exhaustive and that sue
cess will be reached II such O thing be
possible.
1t is now nearly 80 years since the frst
trial Of compressed air was made on the
elevated railroad. Like every other motor
save steam that has ever been tried on the
rails of Uncle Russell Sage's road, pneu-
matte traction air failed utterly there, and
the same may be said Of all the many ex-
periments that have been made since. The
most exhaustive trials ever made here
were entered into two or three years ago
the One Hundred and Twenty-ffth
street line. They lasted a year or more, or
until the corporation making them-not
the railroad company-had sunk all Its
available cash. Then, as the company
could not be prevailed upon to adopt the
new traction, the scheme was abandoned
and the cars were taken of. +.
But the conditions surrounding the
trial will be different and moro
favorable. In the case Of the One Hun
dred and Twenty fifth street line the road
was already equipped with cable traction
which worked to the satisfaction Of Its
A change would have involved
great expense without apparently corre-
spending advantages. The Metropolitan
Traction company, however, is In sore
need of q new system for a part Of Its
work. The cable Is all right for long,
straight lines, doing enormous bust
ness, like the Broadway road, and the de-
pressed trolley Is even better. But the cable
Is out Of the question for the short and
cross town lines, and the overhead
Is forbidden by law, and while the
depressed trolley would work all right on
these lines Its installation would be vir-
tually impractlcable, both because OF Its ex-
pense and for other important reasons.
No Torn Up Streets.
The most serious drawback lies in the
fact that depressed trolley installation
would involve tearing up the streets In
preparation. It was bad enough when
Broadway, the Bowery and Third avenue,
Fourth and Madison avenues and other
north and south thoroughfarcs were torn
up for the cable and the trolley. Street
traffic was disorganized for months in
cases, and the complaints Of the
business men along the lines were both
loud and deep. But even when broadway
affected the resulting Inconvenience
and loss were small compared to what they
- H. -x.-.x. sl.....A wrIt.
the chief cross town lines pass to be torn
up. In such circumstances traffic on ov-
cry one of the main arteries of the town
would be interrupted, whereas only one
1t q time was intcrfered with when the
sable and the depressed trolley wires were
laid.
1t is not denied, however, that the ques-
ton Of relative expense Is an important
one, even with 40 wealthy n corporation
rs the Metropolitan Traction company,
and the saving in first cost of n compressed
air plant compared with that of a cable or
electric plant Is very great. The expense
Of the engines and boilers for pneumatic
will be about the same. OF course,
but the cost Of the compressor will probably
be less than that Of dynamos. The motors
for the cars will vary little In cost from
motors, but there will be no SUBJ
ways TO build and no cables or trolley con-
or feed wires 10 maintain. More
over, n breakdown Mt the central power
unless long unrcpaircd, need not
Interfere in tho least with the operation of
the road, since once It's reservoirs are filed
with packed air each car will be capable
Of running on Its own hook for 10 miles
ne least.
Possibilities Of Expansion.
That cars can be operated through this
agency no doubts. The only points mt
arc economy Of operation and sufi-
tient simplicity Of construction to enable
moformcn OF average intelligence To stop,
start, reverse and control the air engine
without delay or sacrifice Of safety. In
this connection IL should be- born I'm mind
that ~ the air motor must be built ON
practically the same model rs the steam
engine Its mechanism snnot be nearly so
simple as that Of = rotary electric motor.
Naturally. however. many ingenious