Richmond times-dispatch. [volume] (Richmond, Va.) 1914-current, 1920-11-14
DETERMINE ALTITUDE BY
VARYING AIR PREssURES
Employ Instrument Known as Mer-
curinl or Ancroid Barometer
for Purpose.
GREAT MOUNTAIN AscESls
Aerial Navigation Affords More
Rapid and Incomparably Easier
May OF attaining Great Elcva-
tons.

Way OF attaining Great Elcva-
tons.
Il enjoyed your article on B.nch
va ask If ,he altitude OF a place
could not be found hy the difference
4" tnr air pressure at different alii-
"a s I" }. a. wcnona. H."
Yns. that is one of the most used
m'tu"ns nf tinding attitudes The
instrument employed for Tn" purpose
b, a barometer. either a incrcurial or
an auuro!d barometer the former be-
iuV H.. far the better but also by far
n" more difficult TO transport ia as
Iei"iiNcly great size. It's a"h Yard
,JrIu ana its d"licacy Of construction.
~ YOU Viii read some of tho cX-
ir'in"ly interesting accounts Of the
-r.at mountain asccnts. mad" cspc-
rialis in tn" last half Of tho nine
te"uth century by rrof. John Tyn-
-Hl. clarence King. Edward Why!n-
H''" ..na others, constituting unique.
i,5 80. Of literature (Which may
Ii"y,. be- revived now shat aerial
a' .tl!on has afforded NOR. rapid
"nu - incompar"oiy easier way Of
"''aiu'nr great "!"Eati"nD If.
And Instructive narratives. Ia which
steady science clasps hands attn
rr'"tt."ss adventure. you All be i'm
l'TrSe'd NOR" than once by the tx
tIcir" precautions ,akon by tho
,.!'g. US to prot,c, th.ir mcrcuria.
haru. '"'crs from !nJu!y and you vii!
oco's ."naiiy feel sympathetic pang
over tn" unfortunate fatc of On" Of
'lt's, Instruments after 3, had been
got perhaps with days OF toll and
danger. "llnVs. :" ;hc summit Of
walton above the dim earth beneath
u lone would lave been competent
10 reveal.
l., plaipS Principle Of Enr"prtrr.
'rh" principle 81 the barometer you.
80 doubt, know. It's action d.p.nds
uppr the fact that the pressure o; The
'U1oErhcrt d!n'nishcs with increase
OF noight tboV. III" earth. The loss
tho PRESSURE. ana greater the height
sac over tn" mercury Stands IN the
long marrow glass tube. Whom
Whytnpcr climbed ChinbOrazo hc
carried a long barometer IN "a case
strapped to mans back. When.
after days Of gradual struggling up
ward. with intervals OF rest. they at
last reached the treriendous summit
The Wind blew hard from IN.
northeast and drove the light snow
before IL yiciously. We WEI. hum
6rv. vet. numb and wrc;ched, laden
w!th Instruments which could not be
nsci With much trouble, the rncr-
curial barometer Was set uI. one
man grarpCd IN" tripod 20 keep IL
hr.n Will" The Others stood to Wind
VAIL holding up a rHu"h" :" Civ. :,
t..t'c protection The mercury frlI 10
80 inches, with q temperature or II
n"sr,"s Fahrenheit. and lower /;
would not go"
At rca level ,hc barometer stands
near thirty inches. IN. siNt.-u inches
al drop represented. gccordin. 10 Nj.
Hhy'n5crs calculations. - height %:
2oEs5 foot. Ills rcferenc" 10 the t.in-
prrh'ure serves 10 point out Ia" TACT
that nc hrlEh, OF the mercury alone
~ tty' enough to determine. an clc-
yntion
Mercury. as an ordinary ;hernom-
ct.r shows. is affected rs changes
Of temperature even when there !s
no Grange Of elevation. Consequence
IS the temperature at the tire aud
Dlac. OF observation must always be
carefully noted.
Employ Method Of LeveiinR.
i!u' while. with careful work. very
,lcs. approximations to tho true c!c-
vhilpn may be obtained with ncrcu-
tt,l barometer. yet ~" Instrument II
subject TO various slight sources of
rr-pr. and when extreme accuracy IL
required az ia ;he work OF TN" coast
aud gcodriic survey, the method OF
i"v.isnE. which have befor" de-
Scrih"d. is employed
DnJs. however. is very laDorious
wien attempted giHCrE h!Eh and rug
= "a mountains. and. for lofty peaks
TIL results obtained hy baronc;ric
observations are supplemented by yet
another method OF mcaaurcinc
va!ch IS u true surveying operation.
s.a.r Il depends upon IN" US" of q
~ ""ur.d baSel!m- and % measured
'iu..."-. when used In Advantageous
virrunStarccs :his i-'Epuo,ncIric
,t.tod. rs II is c1il"d. 10 ;icub; gives.
'u = tho whole more trust worthy re-
sa than iii" barometer can AFFORD.
Fsr ncasnrm.nts ;ha; must 10
h-#'Ny made. and where E-rat ac-
Urtcy IS not aimed ~. IN" second
."ru ~ barometer. called the an
"ru!H. is very useful This consists
- case partly exhausted %: air.
ana having thin. elastic. metal I'd.
whi-h is very sensitive Ia changes
90 iv" pressure pt the air on lie.
Indicates All Fluctuations.
iI"chaniSm o: d"licai levers In
close! IN the nass magnin"s Tho
ms"Tonen, Of a POINTER attached to
the elastic lid. which swings round
q cni we'd graduated scale OH the ex-
terinr anG thus Indicates directly 10
ne sTc All fluctuations OF the Id
hHe 20 change OF atmospheric pres
These baromc;rrs are often made
"a ~ shape of watch. watch can
"e Garried In thu; pocket They vii!
~ Going from npor'' 1" nD"r. and
they may give considerable salts
rae on 10 curious minded people
VII" Ike 10 keep record "i their
Gps ,nd downS An"rrlds arc now
attached To touring cara. y -ougn
gene H' rule is tina, a fall OF an inch
IN pr"SSur" corresponds 10 an in
"rcS'" OF about 500 feet in elevation.
lri another method o! measuring
heights il afforded by tn. change
mat takes place in The boiling tenn
ncraturc Of water " "a change OF at
l"-phcri: pressure. Professor Tyn-
'ail used to apply this method, some
times with great discomfort to his
exposed hands, in measuring the
i"iSht OF snowy Alpine peaks.
On Mont Blanc ;hc boiling point
~ water or the Centigradc scale Is
ON 50 degrees Instead OF tho 100 at
sea level. y rough rule is that the
hoilinS point falls about degree
i'ahrcnhcit for every 5a5 feet OF AS
cent