/ ‘ Jan. v7, 1947; ‘ ' '\ F. E. TANKSLEY ' . CLINICAL THERMQMETER' ' 2,414,001 ‘ ' Filed Aug; 5, 1944 FopmsrEf Tgzvnszzy ' INVENTOR‘~ r I ' w? W ; ATTORNEY Patented Jan. 7, 1947 2,414,001 UNITED’. STATES PATENT‘ ‘OFFICE CLINICAL THERMOMETER ' 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 2 preferred form of the thermometer of my vin tering thermometers. This type _ thermometer vention; _ ‘ ' 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 inevitable. 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 part 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 is 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 2,414,001 3 4 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. FORREST E. TANKSLEY.