History of the British Thermal Unit

Abstract

THE date of the phrase “British thermal unit” can be pushed back by fifteen years ; it occurs in W. J. M. Rankine, “Manual of the Steam Engine” (1859), p. 300 ; but here, as in the 1875 quotation given by Dr. Powell¹, it is a descriptive phrase and not a technical term ; Rankine is in fact contrasting the British thermal unit and the French thermal unit.

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