Madison times. (Tallulah, Madison Parish, La.) 1884-1???, 1885-09-26
ABOUT THERMOMETERS.
Causes which AFFECT Registratfon.'
The Influence Of Altitude.

''How is the thermometer trade"
asked reporter OF well known dealer
in such instruments yesterday.
az have Just one left" he rejoircd,
STOPPING behind the counter with laugh.
"Since the hot weather set in the trade
has been immense and have sold out
big stock. have ordered lot more,
however. Every body is buying in order
to make experiments and observations.
"The prices of thermometers vary
greatly. Those in common use cost
from % cents up to Sl.50, 81 or So apiece.
The majority sold are of the % and 30
cent kind and, indeed, have disposed
Of but few or none of the higher priced
since this hot wave came on. Occasion
ally a man comes in who is willing to
pay 81 80 for an extra instrument which
he wishes for permanent use, bat such
cases are rare. Men who want to make
experiments and boys who buy for curl
osity get the cheaper kind, which arc
Just as good for all practical purposes.
Don't they vary? Certainly they do
though why I don't know. | have seer
half dozen in window: and scarcely
two registered alike. noticed six yes
terday, believe, in which only foul
agreed with each other"
The fact that thermometers vary j:
well known, but few people think of the
simple explanation. To reporter, who
lipouired the reason of the Assistant Ob
server last evening, that gentleman said
The principal reason is in the impcr
lection of thermometers themselves. Il
is nonsense to suppose that the cheaI
Instruments are reliable. The calibra
ton. that is, the ascertaining of the bas'
lof the tube i'm order to reduce it to {
scale of degrees, is nearly always imper
fact. This has to be very carefully done
to obtain a GOOD instrument, and makers
lcan't afford to take pains with cheaI
ones. -. A.
"Another cause of variation is in the
fact that the temperature of places few
feet or a few inches apart often varies
greatly from radiation or otherwise
For instance. here are two barome
ters in this room not six feet apart, an'
: vet in consulting them / often find ;
degrees difference registered on thes
scales"
Every one almost has remarked tina
. the Sipnal Service thermometer has IN
7 dica.eJ lower temperature than priyat
ones scattered throughout the city. IN
instruments being OF the best make, al
!, sorts of theories have been assigned
! Tho obseryor's Office is in the story O
. the Courier. Journal building and to IT
. height above the earth many have al
y t-ibuted the lower reading:
"This is all a mistake" said the Ou
server. 'Our thermometer register
d lower because it is SO arranged Una
nearly all the radiatated heat is cut OF
With ordinary observers this is ne'e
thought of. 1t is almost impossible I
o find a place where more or less heat
not radiated from walls, pavement
4 buildings or other objects. Consequent
II a thermometer where this is not specia
Iv provided against will always reeiste
a temperature much higher than is reall
l. the case.
d at is extremely difficult to get tn
correct reading Of a Thermometer huI
, in the sun, as people say. The reason
i because SO much depends upon the pt
n sition. see some one stated that
r. Main street thermometer marked ].
degrees. II might have marked Il
degrees in another place at the san
N time. For instance, you may 60 to OF
r of the windows when an eastern WIZ
n is blowing on a hot day, and the M
touch Of the current OF air on your Ia
al will be like the breath ola furnace.
ct Is highly heated in coming over U
It, metal roofs, but its temperature W
10 yary in diffarent positions. OF cour:
" however. a thermometer will alwa
'e register higher in the sun than IN L
re shade.n Louisville Courier Journal.
IcI