Thermo-hygrograph
Encyclopedia
Chart recorder
A chart recorder is an electromechanical device that records an electrical or mechanical input trend onto a piece of paper . Chart recorders may record several inputs using different color pens and may record onto strip charts or circular charts...
that measures and records both temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
and humidity
Humidity
Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...
(or dew point
Dew point
The dew point is the temperature to which a given parcel of humid air must be cooled, at constant barometric pressure, for water vapor to condense into liquid water. The condensed water is called dew when it forms on a solid surface. The dew point is a saturation temperature.The dew point is...
). Similar devices that record only one parameter are a thermograph for temperature and hygrograph for humidity.
A thermograph is usually configured with a pen
Pen
A pen is a device used to apply ink to a surface, usually paper, for writing or drawing. Historically, reed pens, quill pens, and dip pens were used, with a nib of some sort to be dipped in the ink. Ruling pens allow precise adjustment of line width, and still find a few specialized uses, but...
that records temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
on a revolving cylinder. The pen is at the end of a lever that is controlled by a bi-metal strip of temperature-sensitive metal which bends as the temperature changes.