The workingman's advocate. [volume] (Chicago [Ill.]) 1864-1877, 1875-04-24
fR0M PENNSYLVANIA.
FAN HAVEN, ALLEGHENY Co.,



April 10, 1876.
To the Editor Of the woaKnsMAE's ADVOCATE
| see that | am attacked by one OF the
oldest coal operators in Illinois h. says
that my uncalled for assertion is erroneous
concerning Mr.. D. Mcdonald, where say
that Mr.. D Mcdonald knows very little
about the nature of Air and Mine Ventila-
tien. Now, 1 will say again that he does not
prove IT by his last letter In the ADVOCATE,
as well "a by his other letters. will also
show Coal Operator. that czcept he under
stands the nature of Air he is no judge as
to whether other people do or not. Coal
Operator says that to his certain knowledge
Mcdonald has filed responsible positions
for the last fifteen years, and given salts
faction. / do not doubt it at all, but
want it to be understood that years Of ex-
perience alone is no proof that man I'M
derstauds his business, or else where does
the bad tradesmen come from. / know a
man that has been a Mine Manager for
twenty years, and he says bad air is good
for man, and he also asks how can they
ventllate coal mines under ground, mean
ing those entered by shafts. You must
understand that his experience has been
in those hillsides OF Pennsylvania, SO it is
not the amount Of experience alone, nor
the amount of reading alone, nor the
amount of studying alone, that makes a
man learned, but it is the amount that he
remembers of what he has experienced,
read and studied. that makes q man
learned. But enough Of this. l will re-
turn to Mr.. hcDonald's letter of March
II, 1876. Now, he asks what is the cause
Of Natural Ventilation i'll Mines He says
the cause is the natural heat that Is in the
mines that is 50 but he does not give
the proper reasons why. Then he asks
what time Of the year is Natural Ventila-
ton mostly predominant In winter
Whyl Because the atmosphere outside
the Mines is so much colder than the Air
inside the Mines, consequently the weight
of the atmosphere above ground has a
natural tendency to fall or press itself
down into the Mines. In this last asser-
ton he is wrong, for the atmospheric
pressure has nothing to do with causing
the natural currents of Air III Mines, no
more than have with causing the natural
motion of the earth, for the atmospheric
pressure is equal on the top of each shaft
and You must know that equal forces, act
ing in contrary directions, destroy each
others effect, Just as two one pound
weights suspended to opposite ends Of a
beam scale, would destroy each others
effect in moving the scales. Aud then he
asks what ia the cause Of the stagnation Of
air currents In mines through the summer
season, and answers because the air in the
mines is then generally colder, conse-
quently denser, THAI the atmosphere
above ground. Here he is wrong again, for
when the air in the mine is colder than the
air outside, the air will 60 down the shaft
that is highest on top, and not stagnate,
as he says. For this reason, the air in the
upper part of the shaft that is highest on
top Is colder, consequently denser, than
an equal column Of Air outside, the Air
in the upper part Of the highest shaft be-
ing heavier bulk than the warmer Air out
side, falls down by its own superior weight,
thereby produces natural currents, and
not "a d. Mcdonald says, by the atmos-
pheric pressure. And the real cause Of the
stagnation "f air currents in the summer
season is this That the air becomes of
the same temperature both in and outside
Of the mine, and the air in the two shafts
being the same temperature and weight,
balance each other, thereby produce stag
nation, and not as ID. Mcdonald says, by
the air i'll the mI1e being colder than the
air outside. Now he says there are natural
currents OF air in summer in a Mine. and
reverses dozen times day, more OF less
This is different from what he stated in his
former letters, where he states there are no
natural currents of air in any mine in
summer time. did not intend to write
this letter, nor would have done 50. but
for Coal Operator saying my assertions
were erroneous. # Coal Operator under
stands The nature of air, and he makes a
fair and square examination Of my letters,
and Mr.. d. McDonald's, he will see for
himself as for the proper place to put the
furnace under various circumstances.
will state in future letter on shaft Ven
ti@ation the reasons why. w.