IMPROVEMENTS IN MAXIMUM AND MINIMUM THERMOMETERS
Year: 1882

page_text: LETTERS PATENT to Herbert John Haddan, of Kensington, Middlesex for an
invention of IMPROVEMENTS IN MAXIMUM AND MINIMUM THERMOMETERS
A communication from abroad by Heinrich Kappeller junior, of Vienna,
Austria-Hungary.
PROVISIONAL SPECIFICATION left by the said Herbert John Haddan at the
Office of the Commissioners of Patents on the 26th April 1882.
HERBERT JOHN HADDAN, of Kensington, Middlesex, "IMPROVEMENTS IN
MAXIMUM AND MINIMUM THERMOMETERS," a communication from abroad by
Heinrich Kappeller junior, of Vienna, Austria-Hungary,
This invention has for its object to construct maximum and minimum thermo-
meters which are less liable to get out of order and can be read more casily than
those generally used. For this purpose the thermometer consists of a vertical
glass-tube with a bulb at the top and one at the bottom, said tube containing
alcohol up to about the middle of the upper bulb. The continuity of the liquid in
the tube is broken in or near the middle of the tube by a short colutun of mercury,
above which there is a steel-pin fused into a small glass tube from which some
glass threads extend to the walls of the maintube, so as to produce a slight elastic
pressure against the same. Below the mercury column there is a second steel
indicator similar to the upper one. If the liquid in the tube expands in consequence
of a rise of temperature, the mercury rises thereby lifting the upper indicator, and
when the mercury begins to fall the upper indicator remains in its highest position
while the lower indicator moves downward until the minimum temperature is
reached. The position of the two indicators shows the maximum aud uninimum
temperature on two scales, one on the right and the other on the left of the
glass tube.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Herbert Jolin Haddan in the Great Soal Patent Office on the
17th October 1882.
"
"
HERBERT JOHN HADDAN, of Kensington, Middlesex IMPROVEMENTS IN
MAXIMUM AND MINIMUM THERMOMETERS,” a communication from abroad by
Heinrich Kappeller junior, of Vienna, Austria-Hungary
To determine the extremes of temperature, Rutherford's Instrument with two
separate thermometers-a mercurial thermometer for the maximum and a Spirit
thermometer for the minimum-as well as the handy six thermometers of Casell
with Ushaped tube, with double scale and filling of spirit and mercurial indicator
have hitherto almost exclusively been used in Observatories. The disadvantages
peculiar to this kind of thermometers are well known and it need only be pointed
out that Rutherford's instruments very soon get out of order and that the Six
thermometers are transportable with the greatest difficulties only, because, owing
to the width of the tube, the mercury column which serves as an intermediate link
is liable to break and to dissolve into small mercury particles which pass beyond
the indicator whereby-the-instrument becomes entirely useless.
In the construction-of-the-new-instrument_the_disadvantages of_the_former-
constructions have been duly considered and the principal aim has been to produce
as far as possible a simple and cheap instrument which is at the same time reliable !
and transportable. The new maximum and minimum thermometer consists, as
seen in the accompanying drawing, of only oue spirit thermometer having a
straight tube with a wide bulb at the top. -The-tubo-is-filled with alcohol as far
as-to-fill half of the top. bulb. At a convenient place of the capillary tube of the
thermometer the continuity of the alcohol column is broken by a short thread of
mercury ab-(from-5-to-6-degrees long) which rises in consequence of the rise,
and falls in consequence of the fall of the temperature, in other words, it serves-as-
an Indicator of the existing temperature. Below the mercury column is a steel
index & fused into a small glass tube slightly pressed to the wall of the capillary
tube by means of elastic glass threads, above the mercury column there is a second
similar index c. It is evident that both indices are moved by the mercury column
according to the change which takes place in the temperature, viz, the upper index
is pushed by the upper end of the mercury column a as long as the temperature is
rising and it remains at the highest point arrived at as soon as the falling sets in;
the opposite takes place with the second index which is pushed downwards towards
the bulb end of the thermometer until the temperature ceases to fall. Two equally
divided scales, both reading in the same direction and differing from each other by
the length of the mercury column only serve to indicate the extremes of temperature.
The scale on the right side indicates the maximum, the scale on the left the
minimum. To replace the indices for further observations a magnet is used, by
which both indices are again drawn near the mercury column. The most important
part of the improvement consists principally in the extraordinary sensitiveness and
in the graduations.
While the Six thermometers are provided with two scales one of which is
divided in the natural direction, vis from below upwards, as generally found in
thermometers, the other scale, is divided in the opposite direction viz from above
downwards, which according to experience is often the cause of mistakes and
thereby of useless observation.

page_text: manner that the alcohol fills about half of the upper bulb. When the temperature
is normal and that the continuity of the Spirit column is broken by a small
mercury column which according to the rise or fall in the temperature is shifted
upwards or downwards, in combination with two steel indices fused into two small
glass tubes and moveable in the tube of the thermometer indicating the maximum
and minimum temperature arrived at by means of two equal scales arranged in the
same direction, but differing from each other by the length of the mercury column.
2. The construction of a combined maximum and minimum thermometer in a
single straight tube with an upper and lower bulb.
3. In a combined maximum and minimum thermometer the use of two moveable
stcel indices fused in small glass tubes; one of said steel indices being situated
above and the other one below the mercury indicator which is placed about in the
middle of the tube of the thermometer.
In Witness whereof I the said Herbert John Haddan have hereunto set my
band and seal this seventeenth day of October A.D. 1882.
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