page_title: Nephelescope
section_title: Original design
hierarchical_section_title: Nephelescope / Original design
caption_attribution_description: English: Original design of the nepheloscope by Epsy
context_page_description: A nephelescope is a device invented by James Pollard Espy to measure the drop in temperature of a gas from a reduction in pressure; originally used to explore the formation of clouds.
context_section_description: The original design  consisted of an air compression pump (a), a vessel (b), and a barometer (c).
  Air is pumped into the vessel until a desired pressure is reached, the stopclock is then closed and the temperature allowed to equilibriate. The stopclock is then opened, allowing the pressure of the container to equilibriate the atmosphere, and then closed again.
  The air inside of the container would now be colder. As it warms up, pressure inside the container once again increases above atmosphere. This increase in pressure can be used to work out the number of degrees which the container had been cooled by.
caption: Original design of the nepheloscope
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