The workingman's advocate., 1875-03-20
Mine Ventilation.
FROM PENNSYLVANIA.
FAIR HAVEN. Allegheny CO..
Pa. March 2 1879.


Pa, March :. 1879.
To The Editor Il the WoksNsx,N's ADyoC,rt
have read your paper Of February the
10Th. and ny attention was taken by an
article On Mime Ventilation, by a mining
engineer He says that the lower open
iny Of mine having two shafts IN comuni-
cation, Nil be the natural upcast III all
cases, when the temperature Of the mine |
y greater than the air outside Now It j.
lust the reverse Of that, for column Of hot |
air in the NINE will lie much lighter than |
an equal column of colder air outside, |
therefore the higher opening viii hv the |
natural upcast in all cases where the tenn |
perature Of the mine is greater than the |
air outside. Again, be says, the heavier
column must be III the higher opening
where the outer alr is warmer, consequent
Is lighter than the mine air which is a
direct contradiction OF his former assor
ton. but Il is nevertheless true and
then he SAYS the longer shaft because "
its greater length. contains 4 deuser coll
umn That is impossible. for supposlng
We have two shafts one e. be 100 feet
deep. the other to ne 2OO feet deep. ana
level at the bottom where they commune
cate, and the different depths caused by
the different height on the top, then the
natural heat Il the mine Is lust the same
at the bottom 81 each shaft. therefore the
density is just the same, tpr the different
density j. caused by the difference uf tenn
perature. The real cause uf the down
ward motion Of air ~ the 3Ou foot shaft IN
summer 5 this that the air in the upper
half Of the POO foot shaft i colder than an
equal column of hot air outside, conse-
quently denser IN summer, and the reverse
in winter The arr ia the lower half Of
the 200 foot shaft is Just the same tenn
peratr-e and density as the air w the 100
foot siaft, therefore they balance each
other, 20 the motion is caused. as ! before
st.tcd, by II air IA the upper half Of the
deeu shaIt being Of different temperature
te-. CORRESPONDING column Of air outside.
as yea Sc. By reference to MY letter of
February 10Th You will also observe a
mistake "a ~ printing. when | say II
there IS a furnace al the higher opening it
viii be sufficient for It wllI make the air
in the upcast be't.r. should have been
much hotter than tie air outside. even IN
,atnnreT t.he, Consequently produces circu-
lat!on, a. II was IN my letter, providing
ne furnace chimney j. high enough t.
overcome the dcauWarl tendency As for
y. McD. he still says there are no natural
,.rreuts IA summer. That IS true only Ia
q as "ht,, y. tNu shafts are rpud .u
dtptI and level Htth each other at the tpp
Hn bottom, IsIt m srln. and fall. when
'@~- hr temperature j. often the same as that
tie mine, then there are NO natural cur
a-.i ts IN -L-se hillside mines. except 1t is
- ~ the winds blowing iu different
.Itrctl-ns OF the cars moving In ur out
- But Tie cars are artificial power. and III
y.tsa whore the two shafts are equally deep
Iud %syel al the top aud bottom. there are
no uatuTG! currents Of air IN any season Of
Che year. because at equal depths the tenn
rerature Is equal all the year round no mat
Ter whether The shafts are deep or shallow,
Il Is the sane, so that those shafts where
William Hopton SAYS there vas great natu-
tal draughts N winter. and gradually
.eased in summer. were 80 situated that
the currents ia winter we're caused by the
air IN tie upper part Of the higher shaft
being ot greater temperature, Consequently
lighter than All equal column of colder air
outside, and works npon the same prlncipl~1
IS these shafts IN railway tunnel ls---Khen
the air outside is much cooler Chan The Air
inside, It travels " thseft, and when
the teinIsIAI llI1-ls equal M and outside, II
ersffT travels up nor down, fort the density
Of the two columns uf air in and@utslde Is
exactly equal, consequently balance each
other and in case 81 deep mines. Shere
the temperature is greater all the year
round, than the air o. tslde, the shaft
which is highest on top III be the natural
upcast all the year rounC, caused, as ! be
fore stated by the difference Of tempera-
ture OF the air IN the pper part nf the
higher shaft and the air oa, ''de
1t seems to me that Nj VI, D. has never
seen amy mines except thos, entered by
shafts. Ii there was no Other kind Of
mines bat those entered by shafts,
then his argument is not based upon
proper guide, for the days are not
equally hot in summer nor cold in winter,
therefore the proper guide is the difference
Of temperature Of the air in and outside of
the mine, for as the difference Of tempera-
ture 40 viii the natural currents up or
down the highest opening, even in shafts
but when the temperature Is equal i'll and
outside. then there Is no natural currents
ot air in any kind of mines except as I
before sald, =! he winds blowing outside
think shall content myself WiIn these
fe" remarks at present, as they only apply
to the cause Of natural currents under
various circumstances. IL | write any
more think ! shall divide the subject il
parts as follows: Shaft Ventilation. Slope.
Ventilation and Hill Side Mine Ventila-
ton, 50 AS It will be better understood.
W. Fl.