durometer

[Lat. durus hard, and Eng. meter (q. v.).] An instrument invented by Behrens, designed for testing the relative hardne of steel rails. It is virtually a small drilling-machine. working by hand or machine power, which registers the number of revolutions of the drill-spindle and also the amount of feed, the latter being given by the application of a known weight to the back of the drill-spindle. The friction of the machine and the state of the cutting edges are supposed to be constant quantities, and, as such, are thrown out of calculation. The hardne of a metal is sidered to be inversely proportionate to the depth of feed obtained with a given number of revolutions. ( Knight.) *dür-ous, a. [Lat. durus = hard.] Hard. "They all of them vary much from their primitive tenderne and bigne , and so become more duro us." Smith : Port, of Old Age, p. 186. du-roy', s. [Fr.] Fabric: A common quality of woolen serge.