The mirror., 1922-06-22

ne Introduction OF compressed air
hauling locomotives in the St. Gothard
tunnel was a successful turn in favor of
compressed air for railway work, and
seemed to stimulate efforts in that direc-
ton; it was soon followed by the Mekar-
sksi and Beaumont compressed air railway
systems in Europe, with increased air
pressure and better appliances for econom-
ical compression and motor use. Com
pressed air locomotives for mine haulage
continued to improve in constructive de-
tails, and are now largely in use in the
U. S. For mining purposes compressed air
appliances have been steadily protected,
until at the present day there seems to be
little room left for greater improvement
except changes in detail, if such can be
really called improvement.
The use of compressed air machinery
for quarrying, mining and tunneling, and
the means of COMPRISING air along
economical lines, have been greatly ex-
tended by the inventive genius of Bur-
leigh, Ingersoll, Sergeant, Rand, Clayton,
and Others who have contributed to and
promoted the economy of practical opera
ton in rock-boring machinery that has so
greatly aided in excavating the vast sys-
tenn of railway tunnels of the United
States, and in sinking and drifting in the
mines of all countries during the past
quarter of century.
Every implement required in the gener-
alton of compressed air power and its
uses has overflow co its earlier and narrow
field of work, and is now emcompassing
a wide area of usefulness in our work
shops factories, and in hundreds of indus
trial operations; transportation, railway,
appliances, refrigeration-even into the
painting of buildings and structural work,
and the dusting of furniture, carpets and
clothing.
The later development and actual ap-
plication of compressed air at extremely
high pressures, and its economical use by
reheating derived from the persistent ef-
forts of Mekarsksi, Beaumont, and others
in Europe, and of Judson, Hoadly, Knight,
and Hardie in the U. S. have brought
the use of compressed air to a new con-
dition of application, and high pressure
storage of $500 or more pounds per
square inch in a condensed space of from
allows for sufficient storage volume within
the limit of passenger car and vehicle
capacity for runs of reasonable distances.
The precise limit of the compressibility
of air at ordinary temperatures is as yet
an unknown quantity. 1t has been COM
pressed to $4,000 pounds per square inch
in experiments for blasting rock; and it
has been asserted, and there seems to be no
reason to doubt, that any pressure may be
obtained within the limit of safety in the
strength of metals to hold the pressure.
The assertion has been made by expert
menters with high air pressures that TO-
600 pounds or more per square inch may
be made available for special purposes;
this is far below the explosive power of
gunpowder. The blasting effect of air at
high pressure in coal mines was noted in
series of trials at Denton and Wigan,
England, in 1879. During the trials
pressure of 14,2o0 pounds per square inch
was attained by the comparatively crude
methods of those days. AS compared with
powder, the trials were successful in the
saving of time and in the page 8, Col. s)