The Carcel is a former French unit for measuring the intensity of light. The unit was defined in 1860 as the intensity of a

Carcel lamp The Carcel lamp was an efficient lighting device used in the nineteenth century for domestic purposes and in France as the standard measure for illumination. The lamp was invented by the French watchmaker Bernard Guillaume Carcel (1750–1818) t ...

with standard burner and chimney dimensions, which burnt

colza oil Close-up of canola blooms Canola flower Rapeseed oil is one of the oldest known vegetable oils. There are both edible and industrial forms produced from rapeseed, the seed of several cultivars of the plant family Brassicaceae. Historically, ...

(obtained from the seed of the plant Brassica campestris) at a rate of 42 grams of colza oil per hour with a flame 40 millimeters in height. In modern terminology one carcel equals about 9.74 candelas.

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