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Jan. v7, 1947; ‘
' Filed Aug; 5, 1944
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Patented Jan. 7, 1947
Forrest E. Tanksley, Nashville, Tenn., assignor to
Eisele & 00., Nashville, Tenn., a partnership
Application August '5, 194lrseria1 No. 548,232
1 Claim. (01. 73-371)
This invention relates to‘ clinical or'self-r'egisé
preferred form of the thermometer of my vin
tering thermometers. This type _ thermometer
_ ‘
may be de?ned as one which, upon being inserted
Figure II is a cross section view taken along the
in the oral or rectal cavity or other placev the
line A-A of Figure I.
temperature of which it is desired to ascertain the Cl
Referring now in detail to the drawing the nu
mercury column will rise to the proper point to
meral [0 denotes the stem of glass containing the
indicate the temperature upon a suitable scale,
axially positioned capillary bore II. A suitable
usually engraved upon the thermometer stem,
scale (not shown) is engraved upon the surface
but, upon being removed from said cavity, the
of stem l 0 and shows, by the height of the top of
mercury column will maintain its position in the 10 the mercury column in bore II, the temperature
stem, thus allowing the reading to be made at any
to which the bulb I 2 of the thermometer is or
time subsequent to such removal, due to the fact
has been subjected.
that this type of thermometer includes a device
A small enlargement or bulb I2A is formed in
which causes the mercury column to separate into
the bore Hat a point slightly above the main
two parts at some point between the bulb and the 15 bulb I2. The bulb [2 serves as a container for
scale, the lower part of the column receding into
an expansible liquid, usually mercury. A wire or
the bulb as the temperature of the thermometer
rod E3 of metal or other suitable material is po
falls to the ambient temperature, while leaving
sitioned in bore ll between the bulbs l2 and I2A,
the upper portion of the mercury column in the
one end of wire I3 extending a short distance into
highest position it reached during the time the 20 each bulb. The heat of sealing the bulb onto the
thermometer was inserted in the cavity.
stem causes the wire l3 to stick or weld slightly
The device by which the mercury column is
to one side of the bore at the lower end, thus re
caused to divide or separate as the temperature of
taining it in position.
the bulb falls usually is called the contraction and
In practice the diameter of the bore is of the
usually consists of a small, partially collapsed 25 order of .0015 inch and the diameter of the wire
bulb formed in the thermometer bore between the
is of the order of .001 inch. Thus it will be seen
main bulb and the scale portion of the stem. The
that the portion of the bore into which the wire
two opposite walls of said contraction bulb are
[3 extends will be restricted generally to an an
collapsed against each other forming a bifurcated
nulus l4 having an external diameter of the or
passage of reduced cross section as compared to 30 der of .0015 inch and an internal diameter of the
the bore of the thermometer stem.
order of .001 inch. This portion of annular cross
The contraction so formed constitutes such an
section constitutes the contraction which causes
obstruction to the movement of the mercury col
the mercury column to divide when the bulb cools
umn that the cohesive force of the mercury is
oif, allowing the upper portion of the column to
unable to pull the upper portion of the mercury 35 remain in its indicating position.
column therethrough, thus causing the column to
The operation of my new improved thermome
divide at the contraction.
ter is as follows:
The proper forming of this contraction requires
Upon being subjected to an elevated tempera
great skill in manipulation and even under opti
ture the mercury in bulb l2 expands and travels
mum conditions a large percentage of rejects are 40 upward and forces through annulus I4 ?lling bulb
I2A past the upper end of rod [3 into bore II in
It is an object of this invention to disclose a.
which it rises to indicate the temperature to which
bulb l2 has been subjected. Upon being removed
new and novel form of contraction which will
from the source of heat, the mercury contained
serve all the useful purposes of the usual form of
contraction, but which may be made by rela 45. in bulb I'2 contracts and the column divides in
the annulus l4 between bulbs l2 and I2A, the
tively unskilled operators and which will elimi
lower part receding into the bulb and the upper
nate several operations necessary to make the
remaining in its indicating position. It will
prior form of contraction and which will result in
now be seen that the upper portion of the mer
a much smaller percentage of rejects.
The construction of my new form of clinical or 50 cury consists of a very ?ne ?lament of mercury
self-registering thermometer contraction may
best be understood by referring to the accompany
lying in bore ll above bulb I2A joined to larger
mass of mercury located in bulb [2A. Bulb IZA
made very small as compared to bulb l2 so that
ing drawing in which:
temperature variations will not cause appreciable
Figure I is a partial longitudinal section of a 55 movement of the mercury column due to expan
the bore l I due to differences in the coefficient of
sion or contraction of the mercury in bulb HA.
expansion of the two which tends to loosen and
However the diameter of bulb [2A is still large in
remove any obstructive matter.
comparison to the diameter of bore H.
While I have shown bore II and wire 13 of
The cohesive force of the mercury globule in
circular cross-section, it is understood that the
bulb IZA resists any change in the form of the
cross section of the bore ll' and/or the wire or
globule and thus this globule of mercury tends to
rod member l3 may be polyangular, oval, ?uted
anchor the upper portion of the mercury column
or of any other suitable form.
in position and resists any movement thereof due
While the invention has been described in lan
to any ‘slight differences in gas pressure on the
upper and lower ends of the upper portion of ‘the 10 guage more or less speci?c as to structural fea
tures, it is to be understood that the invention is
mercury column. After the reading has been
not to be limited to the speci?c features shown,
taken the upper portion of the mercury column
but that means and construction herein dis
may be caused to rejoin that in the bulb by shak
closed ‘comprise the preferred forms of putting
ing it down in the usual manner.
"my invention intQ'e?ect, and the invention is
I have observed certain'other advantages -of
therefore claimed in any of its forms or modi?
my construction. The presence of-th‘e metal wire
cations within the legitimate and valid scope of
in the bulb and bore causes thermometers made
the appended claim.
in this way to reach their correct indicating po
A'cli'ni'cal or self-registering thermometer com
structed in the usual manner. This seems to be 20 prising a stem portion having a, small bore there
through, ‘a main bulb for vcontaining a thermo
due to-the superior heat conductivity of the wire.
sition much quicker than thermometers ' con‘
A further advantage observed in my new con
struction is that it is not subject to clogging by
minute impurities in the mercury. Upon heating
and cooling there seemsto be a relative move
ment between the ‘wire or rod 1-3 and the walls of
expansive ?uid, a small secondary bulb formed in
said bore and slightly above the-main bulb, and
a wire anchored and retained in the bore between
the two bulbs andpartially plugging said bore.
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