Glossary D

Differential thermometers refer to thermometers capable of measuring or indicating the (generally small) difference between two temperatures. Often called thermoscopes, they were commonly used to study thermal radiation. They consist of a capillary U-tube closed at both ends by two glass bulbs. In the tube is inserted a drop of liquid serving as an indicator. When one of the two bulbs (which is often blackened) is exposed to a source of thermal radiation, the air in the bulb expands, pushing the drop along the capillary tube toward the second bulb.
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Thermometer (Messmittel zur Anzeige von Temperaturen. Da ...)
Differential (Differential refers to a device - usually made ...)
Thermometer (Thermometer refers to an instrument for ...)
Indicator (Indicator is identified as an observed value ...)

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Definitives refer to the stamps in general use, often of small size and featuring a monarch or other national symbol. These stamps are usually on sale for at least five years.

Digital camera makes reference to a type of camera that stores or captures the photographed images electronically - I an electronic imaging sensor that takes the place of film. The images are downloaded into a computer where they can be manipulated in a manner similar to scanned images.
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Camera (Camera is described as the most important tool ...)
Digital (Digital refers to a signal that consists of ...)

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