IMPROVEMENTS IN THERMOMETERS
Year: 1876

page_text: LETTERS PATENT to Gustav Wilhelm Schumacher, of Portland, in the County
of Cumberland and State of Maine, one of the United States of America,
Manufacturer, for the Invention of "IMPROVEMENTS IN THERMOMETERS."
ealed the 9th June 1876, and dated the 22nd April 1876.
COMPLETE SPECIFICATION filed by the said Gustav Wilhelm Schumacher at
the Office of the Commissioners of Patents on the 22nd April 1876,
GUSTAV WILHELM SCHUMACHER, of Portland, in the County of Cumberland and
State of Maine, one of the United States of America, Manufacturer. "IMPROVEMENTS
IN THERMOMETERS."
My Invention relates to a registering thermometer operated by the contractile
and expansive power anu property of two hard rubber arms, the more particular
operation of which will be herein-after described. These arms are so arranged and
adjusted that one of them is permitted to expand and contract in such way as to
move levers attached at both ends of another arm, by which movement the
operations of the instrument are effected.
In the accompanying Drawings,―
Figure 1 shows a front or face view of my Invention.
Figure 2 is a detailed view showing the arrangement of the lower lever, and the
connection of the rubber arms with the same.
Figure 3 is a detailed front view; and Figure 4 a cross sectional view of one of the
rubber arms showing their corrugations.
Same letters show like parts.
The arm first above referred to is indicated at a, the other at b; the arm b has
attached to it two levers c and d. The arm a is fixed at its upper end by means of
a set screw e working in a screw hole in the piece f; g is a plate containing the
register or scale, and upon which are marked off the different degrees; his the finger
or indicator, which, at its lower end points out upon the scale the different degrees
of temperature as it is moved by the contraction and expansion produced by heat
or cold. The indicator h is rigidly attached to a small sleeve surrounding a small
stud or pin i, which stud or pin is inserted into a back plate j. The indicator h
and the short lever are both rigidly attached to the sleeve.
As the rubber arm a contracts or expands it moves the lever & upon its pivot l.
The long arm of this lever is attached to the lower end of the arın b, which arm at
Price id I

page_text: its upper end, as before specified, is attached to the lever . Thus the movement at
the end of the lever d, where it is connected with the rubber arm b is increased from
that produced on the short arm of this lever, where it is connected with the arm (
This movement is also
in proportion as the long arm is longer than the short one.
assisted by the contraction and expansion of the arm b.
The movement of the indicator produced by the contraction of the arm a is such
as to show on the registering plate low degrees of temperature, and the other
movement higher ones.
The use of the set screw e is to place the point of the indicator at the proper
degree on the registering plate when the thermometer is adjusted for actual use.
This may be done by obtaining the correct degree from a reliable standard, both
instruments being at the same degree of temperature; m is a spring bearing upon
the indicator h, and tending to move the same upwardly on the scale of the reges-
tering plate. When the arm a with its other arm bare subjected to cold, and con-
tracted, they move the indicator downwardly on the scale, and against the force of
the spring m. When the arms are expanded by warmth the spring m moves the
indicator upwardly on the scale so far as it is permitted, to do by said expansion.
On the front of the registering plate is set a curved rod n, or any equivolent
device. This is to receive two movable pointers s, which are impelled on the
rod or track by the indicator h. The purpose of these two pointers is to record
extremes of temperature during an interval of time in which the thermometer
may not have been consulted, or if the change of temperature is only in one
direction, to show the difference between the time when the regestering plate was
last examined and some other time when an examination is intended to be made.
These devices will of course remain at the extreme points to which they are im-
pelled by the indicator. The arms a and b are corrugated in order to expose to
the action of the temperature of the air the largest possible amount of surface.
When exposed to cold the contraction of the arins acting upon the levers, as
described, causes the indicator so to move along the scale as to indicate the proper
low degree of temperature and heat or warmth and the consequent expansion,
permit the spring m to operate the indicator to such an extent as will show the
proper opposite degree of temperature. The spring m also serves to maintain a proper
strain upon the different parts of the thermometer, and prevent "play" of the same,
so as to ensure as nearly as may be an exact operation.
What I claim as my Invention, and desire to secure by Letters Patent is,-
First. The hard rubber arm a in combination with the lever d, arm b, lever
and the indicator h, the same operating to point out different degrees of temperature
upon a registering plate or scale as herein described.
Second. The arm a, with its adjusting set screw e and piece f with the lever d,
lever, indicator, and scale, as set forth, and with the arm b.
Third. The combination of the rubber arms a, b, levers d, le, indicator 1, and the
registering devices moving on the curved rod, as described.
Fourth. The two corrugated rubber arms arranged and combined, as described, to
operate the indicator of a thermometer so as to show in connection with a spring
pressing upon said indicator different degrees of temperature, as set forth.
In witness whereof, I have hereunto set my hand and seal, this Twenty-third
day of March. A.D. 1876.
GUSTAV WILHELM SCHUMACHER. (L.S.)
Witnesses,
FRANK H. JORDAN.
WILLIAM HENRY CLIFFord.