The Maryville times. (Maryville, Tenn.) 1884-1944, 1896-09-10

the circumambient atmosphere.
Now If the air be used In this condl-
ton, technically known as cold" 1t will.
as have already noted, realize an eff
ficiency Of so per cent. or more. But If,
as 1t Is released 1t Is passed through
heater or passed through superheated
| hot water 1t WILL under the well-known
| has been found possible to add one
horse power to each horse power Of COM
pressed air for one-eighth the original
cost of compression. One form of heater
that has been devised adds 35 per cent.
of efficiency with about this expenditure
In the shape of coal burned.
Adding to the efficiency of the COM
pressed air when used 'cold," to the
amount Of power developed by relocating,
| 1t will be seen that the total amount Of
power realized is about equal 10 the pow
err expended in generation.
| theoretically the total efficiency is act
ually greater, but 1t is a matter Of fact
in practical use 1t Is slightly less. IL is,
nevertheless, true, that in tests made on
| the Hardie street car motor II has been
found possible to realize about per cent.
more energy or work from given guam
| tity Of air COMPRISING apparatus and
using this air, under relocating, in the
Hardie motor than as If the coal were
put into an ordinary locomotive and
used directly for the generation Of steam
| power The apparent paradox Is due to
| the added power gained from reheatlng
| the air.
Comparing American and Partisan ap-
| planes again, the efficiency developed
under the Popp system in Paris, with re-
| heating, Is stated at from go to 70 per
cent.-73 per cent. being given as the
=, maximum. Assuming loss of from 3
| to 5 per cent. under the American
| method, 1t follows that the degree of
| efficiency realized under the Popp sys-
| tenn Is something more than 20 per cent
less than that attained in this country.
| 1t is to be noted further that compressed
air began to be used in Paris long before
| 1t was taken up in this country, the
Mekarski system of surface, transit alone
having been in operation for more than
| ten years.
With the perfection COMPRISING ap-
paratus, and the reheating system, has
come a third important development,
which has chiefly made possible the use
Of compressed air for street cars This
| Is the invention Of what is known as the
Mannesman tube for the storage Of the
air. The latter is simply seamless tube
| or flash, made Of mild steel of any de-
sired size and capable of receiving and
holding air charged to very high pres
sure. Up to the time of its Introduction
| 1t had been practically impossible to
provide suitable reservoir or holder.
Those which were employed were enor-
| mously heavy, took up a whole i'm
| practicable amount of space. The loss
| in one way or another was very great.
The Mannesmann tube solved the prob
lem by providing chest that was prac-
tically air tight, that if it burst did not
| fly In pieces, but simply ripped as would
leather bag and was therefore not a
hazard to life; 1t was light and 1t took
up very little space.
These tubes are now made to carry al
| most any charge Of air. In the case of
the Hardie motor their testing strength
is 1000 pounds per square inch and their
maximum charge about 1000 pounds.
These steel cylinders are distributed un-
derneath the seats and under the car
body in such way as not to infringe
upon the room Of an ordinary street car,
and hold fifty-one cubic feet of air, suf-
ficient to run the car fifteen or eighteen
miles. For the reader apprehensive of
sitting over so highly charged device;
1t may be stated that the whole effect
Of an explosion Of one of these tubes
would be loud report, rush Of air and
a slight disturbance of the atmosphere
Immediately adjacent. There would be
no flying pieces Of pipe, no steam or hot
air to scald, and all you would see after
ward would be an ugly rent In the tube.
Such Is the rough outside of the i'm
portant elements Of the advance in the
art. The improvement in the devices
for compression represented economy of
nrO1IIntion tha 1aua1nnrnapt nf the 70
heating process represented large gain
in the amount Of power derived from
the air, and in consequence still further
cheapening, while the seamless tube Of
fered at once safety storage and insur-
ance from loss.
By virtue of these improvements the
reduction in the cost Of manufacture has
been very great. AS computed by Com
pressed Air, to the editor of which I
am indebted for much Information, air
may now be compressed to high pres
sure for considerably less than 3 cents
per 1000 cubic feet.
1t is probable that air could be COM
pressed, piped through large city and
sold at profit for cents.
When we consider the probable future
of the new force, as such 1t may fairly
be called, we live over again our ex-
immediate conclusion after a survey of
the sufficiently marvellous things that it
can and actually does do, is that there
Is hardly limit to be set to it's posi-
bllities. But brief calculation will de-
fine its limits with some accuracy. To
compress a given quantity of air re-
quires given amount of power, and the
result to be realized in work cannot be
greater than the amount of power en-
ployed in generation. Otherwise you
have perpetual motion-a proposition
that is not patentable and Is otherwise
open to suspicion. 1t follows with q
reasonable degree Of cogency that COM
pressed air will not be utilized save
where, by reason of greater utility or
convenience, 1t Is economy to convert
your original power into this form of
potential energy. 1t is probable that
compressed air will be used to run rail-
way trains or steamships, although it is
conceivable that 1t might be valuable in
days to come, when we shall fly through
the heavens.
But on the other hand compressed air
Is superior to steam piping or any form
of shafting for the conveyance of power.
A long series Of tests at the Pullman
shops near Chicago have demonstrated
the immense economy which lies In its
use, and 1t will therefore be universally
introduced at these works, as 1t Is in
many other great car shops, as in Jersey
City, Topeka, Omaha and elsewhere.
By far the largest use, however, will
come when compressed air is manufac-
tured in huge central stations, similar
to that of the Pop system in Paris, and
is distributed in mains and sold COM
mercially lust as are gas and wainr and