bois de vache

18th and 19th century (French) fur trapper term for the use of dried buffalo excrement in place of firewood, a practice adopted from Native Americas of the great plains.

(literally, "wood of the cow" or "cow wood")

Messrs. I implore you, given the frightful chill on this expansive and treeless prairie, might you be so kindly disposed as to collect for us some bois de vache so that we might warm our bodies and lift our spirits?