ASPERITY

, signifies the inequality or roughness of the surface of any body; by which some parts of it are more prominent than the rest, so as to hinder the hand, &c, from passing over it with ease and freedom; and thus producing what is called friction.—Asperity, or roughness, stands opposed to smoothness, evenness, politure, &c.

According to the relations of Vermausen, the blind man so celebrated for distinguishing colours by the touch, it seems that every colour has its peculiar degree and kind of asperity. He makes black the roughest, as it is the darkest of colours; but the others are not smoother in proportion as they are lighter; that is, the roughest do not always reflect the least light: for, according to him, yellow is two degrees rougher than blue, and as much smoother than green. See Colours.

ASSIGNABLE Magnitude, is used for any finite magnitude that can be expressed or denoted. And,

Assignable Ratio, for any expressible ratio.