IMPROVEMENTS IN APPARATUS FOR REGULATING TEMPERATURE, FOR RECORDING TEMPERATURE, AND FOR ACTUATING TIMEKEEPERS
Year: 1866

page_text: PROVISIONAL SPECIFICATION left by Robert Shaw at the Office of the
Commissioners of Patents, with his Petition, on the 10th January 1866.
I, ROBERT SHAW, of Blantyre, in the County of Lanark, North Britain, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN APPARATUS
FOR REGULATING TEMPERATURE, FOR RECORDING TEMPERATURE, AND FOR ACTUATING
TIMEKEEPERS," to be as follows, that is to say :-
This Invention relates to improved apparatus contrived to act or to be acted
upon by changes of temperature in such a way as to effect the regulation of
temperature by adjusting an air valve or the like. The improved apparatus
can also be modified to record changes of temperature or so as to actuate
timekeepers.
All the modifications of the apparatus comprise in each case a lever which
is movable about a centre, and, which consists of or has fixed to it a tube
having vessels connected to its opposite ends. At one end of the tube there
is formed or fixed a vessel or enlargement which is open to the atmosphere
at the top. At the other end of the tube there is a second similar vessel
or enlargement, but the top of this communicates with a third vessel which
is otherwise closed. Alcohol or other suitable expansible fluid is put into
the third or innermost vessel, and by preference, so as to quite fill it at
the lowest temperature to which the apparatus is likely to be exposed.
Mercury is then put into the two other vessels and tube in such quantity as

page_text: to about fill the first or outer vessel at the highest temperature to which
the apparatus is likely to be exposed. This thermometric lever (as the
apparatus may be termed) is in one modification counterbalanced by means of
adjustable weights so as to be horizontal at whatever temperature is decided
on. Then if the temperature rises, the alcohol becoming expanded acts on the
mercury, and forces some of it from the middle or second vessel along the
tube to the outer vessel, thereby causing the outer end of the lever to pre-
ponderate and descend. When the temperature falls the opposite action takes
place, the alcohol contracts, and the atmospheric pressure forces some of the
mercury from the outer vessel along the tube to the vessel at the other end,
the outer end of the lever thereby becoming lighter and rising.
In applying this apparatus to regulate temperature it is fitted up in the
hall, church, greenhouse, hothouse, stove, stable, bedroom, or other chamber
or enclosed space, and is connected by cords passing over pulleys or in any
convenient way to an air valve communicating with the external atmosphere,
and its action is to regulate the admission of air in accordance with the
internal temperature.
In some cases the thermometric lever is counter-
balanced or partly counterbalanced by a weight placed below the line of the
lever, so that as the outer end of the lever descends from increasing
temperature, and the weight rises, the leverage of the weight will increase,
and thus continually counterbalance the mercury transferred; the lever,
however, assuming a different position for each degree of heat. A recording
thermometer is made by arranging the lever in this way, and by connecting
to it a pencil under which a piece of paper is by clockwork made to move
slowly. The thermometric lever is made to actuate clockwork simply by
fitting it with spring pawls which gear with ratchet wheels connected with
the clock, so that the descent of the lever will turn one ratchet wheel, and its
ascent the other.
It has been experimentally ascertained that a thermometric lever con-
structed as herein-before described can be made to develop ample motive
force for the specified purposes without being at all inconvenient in size.
The tube and vessels are by preference of glass and may be protected by an
external casing. It is preferred to make the vessel containing the alcohol
of very thin glass, and so as to present as large a surface as possible in order
that changes. of temperature may act as rapidly as possible on the alcohol.