Casella Maximum Thermometer

This Phillips-type mercury-in-glass thermometer is attached to a white porcelain plate on a wooden board that is designed to be hung horizontally. The plate is marked "MAXIMUM" and "L. CASELLA, Maker to the Admiralty & Ordnance, LONDON" and "12975" and is graduated every 5 degrees F. from -25 to +130. The thermometer has a spherical bulb; the back of the stem is milk white; the front of the stem is marked "12975" and is graduated (but not numbered) every degree (presumably Fahrenheit) from -26 to +130. Casella trade literature notes that this thermometer was designed "for registration of temperature in shade," that the thermometer was "engine divided on the stem," and that the "improved" porcelain plate "effectively resisted "frost and all effects of weather."
As in the form described in 1832 by John Phillips, a British geologist, this thermometer has a small air bubble near the top of the mercury column. As the temperature rises, the detached bit of the mercury is pushed up; and this bit remains in place when the temperature falls.
This example was owned by John William Draper or his son Henry, both of whom were accomplished men of science.
Ref: D. J. Warner, "Casella and Phillips' Maximum Thermometers for Meteorology and Medicine," Bulletin of the Scientific Instrument Society 115 (2012): 36-38.
Currently not on view
Object Name
maximum thermometer
date made
L. P. Casella
overall: 14 in; 35.56 cm
place made
United Kingdom: England, London
ID Number
accession number
catalog number
Measuring & Mapping
Thermometers and Hygrometers
See more items in
Medicine and Science: Physical Sciences
Thermometers and Hygrometers
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
John William Christopher Draper and James Christopher Draper

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