DURING research on the contact of solid surfaces we have been examining the deformation under load of single asperities. These are formed by turning cones of base diameter about 0.2 mm on metal surfaces and are pressed against a hard anvil under known loads. The resulting flats are examined by relocation profilometry1 and by optical microscopy. The procedure is equivalent to a Mallock hardness test2; Mallock's original tests, in fact, were made on cones of a similar size.