Telegram-herald., 1888-02-17
THE THERMOMETER
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hI-ieH ~ altFzts x eogpsr tk1s Instrument
wss sl.lgzesed apou, zaa iEs Gslseis gFat1aliY
Fel1ose3 81 stLers. sas Is sas HALEY, fEs
f4lBslz Eag .sl zatroAoElsF. ssa0 arst pro
Fosed ths use of lsreaFy - 6Eii f0r tns
tsrr rsaon1eter
There ars nov three kiais cf tLrrnlon eters
ia eD1snoa ase lhFoug iost ia work. blt ths
form iays4esd by Pro1cssof Da4lsl FaATen-
hsir. IA .zxsaisla Dsfal4n "a tie year 100,
aad fro4a sa9Ea tAe Lsssruneas has bsea
E4llsd. - tze one ssnerailY slnpsUysd "a tbs
eas1try, AAd vita Whlca leariy every Intel
lissnt family "a the l4HS . provided. though
tie ''eea1igrzsie tsernsnstsrH = really the
naosr eoavsaisat AID IS n0s adop-ed Ia ali
countries as ths s-zAsi4Et scals fOr scies.sa,
rsfsreacs. and Ike t..s msllo system. is
g@neral aze ia this country = toaosjezs merely
a question ~ tilse.
Mercury osis 3ad vapori1s3 at = tsnpera-
tuFe o. 10. degs Fshreaheit and for OBTAIN
ing any hizbef tesnperatcre than tais a me-
tall.e iastramsuE called n. pyronetsr IS
ulads use Of. bus It's Indications are unrsli-
aole. knd ,e- it remains 10 discover soals
more aocusAts slstAosl ~ MEASURING degrees
Of heat hsr tA1a CD dexs. by TIE Fahren-
he. therE4oEleter Al temperature OF .
deg below zero mercury frsezes and be-
"A a. l. e.
tner an4 fer loas- taglp peratures. pure alco-
hol sp4rits q wlnel cOl1red red With car
mine. ID usually employed. ous Ss ia the case
q tas pryosnessr, - Indications cannot be
depended upoa for ACCURACY. Fahrcnhelt
was not sioss 70 recosnizs the advantages
possessei ,, mercury - a auld for the tube
Il tao thermometer. Mercury, as an excel
leut conductor Of heai. Is vastly mere sus-
cey,ibis 10 tAs changes oc temperature than
al other aaiGS L IS tauca mose easily OBJ
tanned IN a perfectly pure state than alcohol.
Naich, even when prepared With tho greatest
ears, often contains air es well 80 othsr ad
mixtures. and alcohol Is sometimes rendered
thick Oy great degrees OF cold, AID under the
higher degrees Of heat it expands excessively
and ununformly.
rHE ZERO POINT
IL the Fahrenheit thermometers the space
between the freezing and boiling point OF
water is 1ividsl into $50 equal parts or de-
grees, the former being - cegs axd the latter
: L. dezs aSove zero, which was 50 called by
tie inventor from the fact that he supposed
il 70 indicate tho point Of absolute Geld, or
thc very lowest degree that could be pro
dgced aad measured BY any instrument. But
the lowest degree o. cs.d possible to be o5-
tainsd Is NOW estimated TO be 40 days and
the greatest artificial cold ever produced is
g degs. by the Fahrenheit Thermometer.
The zero point Of Thermometer does not IN
Glcato ihe total absence of Lest. a. commonly
supposed aad tae term seeMs u Imply, for an
ahsoiate zero OF teunE erasu4e he's never yet
been attained, ard h3s only ocsH aprroxi-
na.ely dc-e-tninesl though IL Is considered
'.coavonient IS "a idecl starting po.nt" The
zs-o Il = Fs'reassls tberfEo-lSscr is the
temperature Of c mixture of ice aAd comm n
s.Jt. which Is usually employed II tie opera
tioa OF freezing ice cream.
The zero point Of = thcrn0meter should al
ways IS carefully verified, ua.eszs the irstru-
rent ia known % % correct TO DO this I'M
rnerse tho bulb IA vessel filed with saow or
pounded ice. and pres slightly layer Of sew
eral inches areuad IL. so tli2s tne stem. which
should 10 exactly perpendicular, Is covered
with snow - high as the freezing poiat on
tn sale Do this in a room, the tspnpSsturr
OF which is above the freezing poiat, ss that
point iadlcases the temperature OF melting
snow. Thsn in abSat half an hour read At,
taking care 70 have the eye exactly rerpoa-
dicglar % the column of mercury, and NOV
ing the Thermometer freely about ia the mix
TIRE IN caso the top OF the mercury and
tho freezing point Ga the scale do net cor
respond. nsos tks difference. Some iastru-
mcnts are 50 constructed as TO adInit of loos-
suln. tho screws and sliding the glass sale
holding the mercury Up or down dIs,snce
equivalent to the error. but il is not aavlsa-
bls 70 make frequent Wecs =niral changes Of
this kiad The erection ABOVE Indicated
should 10 applied 70 eaea reading of TIC
scale Arthur K Barrett in Detroit Free
Press