Psychrometer
date: label: date made
content: 1851
name: label: maker
content: Fastré
notes: label: Description
content: The inscription on this psychrometer reads "Fastré ainé, Rue de l'Ecole Polytechnique 3, a' Paris, 1851é." The associated invoice indicates that "Monsieur Guyot" bought it for 80 francs in 1851 (along with 3 other Fastré instruments for a total cost of 155 francs). The invoice also gives the "Comparaisons des Thermometres," which allow the arbitrary divisions on the thermometers to be converted to degrees Centrigrade. Since the thermometers were not uniform, they had to be calibrated individually. In a letter to Joseph Henry, Guyot called Fastré "the best living maker of thermometers."
label: Description
content: A psychrometer uses the difference in readings between two thermometers, one with a wet bulb (ventilated to cause evaporation) and the other with a dry bulb, as a measure of atmospheric moisture. Although the phenomenon of cooling by evaporation was discussed as early as the 17th century, the form of this instrument dates from the early 19th century. E.F. August, of Berlin, coined the term in 1828.
label: Description
content: Arnold Guyot was a Swiss scientist, who immigrated to the United States in 1848. He was a major consultant to the Smithsonian Institution as it established and coordinated a network of meteorological observers. He helped with selecting and equiping the sites of the observing stations, writing the "Directions for Meteorological Observations," and preparing the Smithsonian's first Meteorological Tables (see <i>Smithsonian Miscellaneous Collections</i>, vol. 1, 1862). Although the Smithsonian's weather service was of short duration, it was a key element in the development of a national weather bureau
label: Description
content: . .
label: Location
content: Currently not on view
place: label: place made
content: France: Île-de-France, Paris
setName: label: See more items in
content: Medicine and Science: Physical Sciences
label: See more items in
content: Measuring & Mapping
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 1995.0162.01
label: accession number
content: 1995.0162
label: catalog number
content: 1995.0162.01
objectType: label: Object Name
content: psychrometer
physicalDescription: label: Measurements
content: overall: 4 cm x 51 cm x 8.5 cm; 1 9/16 in x 20 3/32 in x 3 11/32 in
label: Measurements
content: overall: 1 1/2 in x 20 1/8 in x 3 1/8 in; 3.81 cm x 51.1175 cm x 7.9375 cm