Evening star. [volume] (Washington, D.C.) 1854-1972, 1903-10-31
THERMOMETERS.
The Processes of Manufacture Are
Most Interesting.


The processes of manufacture of the Their
mometer are such as to interest the most
pronounced hater of technicaLties. One
begins to feel at home when he sees girls
blowing bubbles, even if they are glass
bubbles; he is distinctly tickled when In
the interests of his education, bulb is
shattered and the drops Of mercury chase
each other wildly over the slab until they
meet and form one drop; he is amused.
too, and feels awfully foolish, don't you
know" when asked If he can see the
runs in the discharge of Its daily duties In
some of the smaller Thermometers This
bore or hole, in the center of the glass
tube Is so fine in, say, clinical thermome-
tiers (the variety to be taken in the
mouth'D that you need be proud of your
eye If you can see it; it Is as fine as SILK
thread. and were not the mercury and
alcohol somewhat colored their rise and
fall would be imperceptibe. Alcohol is
here devoted to a laudable purpose. 1t
comes in handy where mercury fails, tnat
is. about and Immediately above freezing
point. To be sure, mercury equalZes Things
In the higher regions Qt does not boil till
600 degrees centigrade) where spirit Their
mometers would be of no use, GO or 20 de-
gress being as much as they can stand:
In the very important details OF marking
off the various degrees the temperatures Of
melting ice and boiling water are taken as
definite points. and these aScertained the
| intermediate degrees are readily
off. To determine the freezing point. the
tubes are stepped for some fifteen or twen-
ty minutes In melting ice, and are then
marked by the operator; similarly. the
bulb is nclosed in the steam over boiling
water until boiling point is indicated. and
that also is marked on the glass tube 1t
may not be superfiuous to add that in the
Fahrenheit scale 80 degrees represents the
freezing point and 212 degrees boiling point.
In the centigrade scale these points are
represented by zero and 100 degrees, re-
spectively.
When in doubt, therefore about the con-
duct of the family thermometer just ad-
| minister to it a snow bath assuming, Of
course. that it is snow season, IT not, use
| melting ice). Determine freezing point, and
| you may restore that useful piece of
furniture to its wonted place on the wall
Initiate the weather men" by giving the
thermometer plenty of air and shade, but
not on the north side Of the house, as that
would be too much for its delicate consti-
tuition. The alterations of the thermome
ter rarely traceable to flaws in manu-
facture. and when they are it never
amounts to more than a degree and half
This you have on the authority of ]. NJ
Taylor. a member of great firm of me-
neurological instrument manufacturers in
this city who supplied the f"cts for this
article
Every precaution is exercised to insure
accuracy in these important instruments,
and the better kinds are kept in stock at
| least twelve months to effect this end. The
stock of this particular kind of instrument
kept in the Hill street plant runs up to a
gddy height of figures. More han 10000
were lying on a few shelves. An interest
| ing instrument used in the United States
weather bureau was pointed out. Scien-
lists hitherto have held that mercury rises
only in a concal shape, thus initiating
against dead accuracy; this thermometer is
| so perfected. however (all impurities be-
| ing extracted from the mercury, that the
notion is now exploded.
Most of the glass used at the works
| comes from Corning, though for many of
| the finer kinds of instruments glass is
imported from Germany. 1t comes in long
strips or tubes, never more than a half
inch In diameter. The ''bores' through
these tubes vary in size, but must be uni
| form in their particular size: there are
two "bores.' round and fat alcohol being
| used in the round and mercury in the fiat
| bore 1t may be mentioned that the
highest registration taken and by mercury
| is 1,c@ but in that case pressure has to
be put on to prevent the mercury itself
| from boiling.
| Another ingenious instrument was pointed
| out. and it will be readily recognized as
| It is in fairly common use, namely the
| ''self-recording thermometer" This con-
! sists actually of two thermometers fixeo
| horizontally to the same frame. a mercu-
| rial and an alcohol, with their bulbs at
| opposite ends of the frame. This inStru-
| ment indicates the maximum and minimum
| temperatures in the interval since last set
1 Above the mercury is a small indica tor.
| which as the mercury expands is pushed
| before it, but in the contracting or falling
| is left behind, the end of the indicator
| nearest the mercury marking the highest
temperature recorded by that thermometer
| Capillary force prevents the indicator from
| entering the mercury. In the spirit Their
| mometer the liquid freely passes the indi-
| Gator when rising, but in falling brings it
| back, the minimum temperature of that
| thermometer being marked by the point
| OF the indicator furthest from the bulb:
| To set this instrument, incline the frame
! tin the Indicator falls back to the surface
| of the mercury. and the spirit thermom-
| eter will simultaneously set itself