Carcel was a French unit of light intensity .
In 1860 the unit was defined as the light intensity of a Carcel lamp with a standard burner and chimney, operated with 42 g rapeseed oil (from the seeds of Brassica campestris ) per hour and with a flame height of 40 millimeters. The Carcel unit is named after the Parisian watchmaker Bertrand Guillaume Carcel (1750–1812).
Converted into the current unit of light intensity is
- 1 carcel = 9.74 candelas
- Peter Kurzwell: The Vieweg unit lexicon. Friedrich Vieweg and Sohn Verlagsgesellschaft mbH, Braunschweig / Wiesbaden 1999, ISBN 3-528-06987-2 , p. 69.
- Russ Rowlett: Carcel entry . In: How Many? A Dictionary of Units of Measurement . University of North Carolina at Chapel Hill. Retrieved May 13, 2009.
- Carcel definition . In: Webster's Revised Unabridged Dictionary, published in 1913 by C. & G. Merriam Co. . The Free Dictionary. 2009. Retrieved May 13, 2009.
- SF Johnston: History of light and color . eknigu Science Library. February 23, 2004. Retrieved May 13, 2009.