Thus far the results accord with other investigations; but in the course of his operations Mr. Cushing also noted this fact, that the grooves produced by the flaking of the flint or obsidian all turned in one direction. This proved to be due to the constant use of his right hand. When the direction of pressure by the bone or stick was reversed, the result was apparent in the opposite direction of the grooves. So far as his observations then extended, he occasionally found an arrow-head or other primitive stone implement with the flake grooves running from left to right, showing, as he believed, the manipulation of a left-handed workman; but, from the rarity of their occurrence, it might be concluded that, as a rule, prehistoric man was right-handed. When Mr. Cushing reported the results of those investigations into the arts of the Stone Age, at a meeting of the Anthropological Society of Washington in May 1879, Professor Mason confirmed from his own observation the occurrence of flint implements indicating by the reversed direction of the bevelling that they were produced by left-handed workmen. Mr. Cushing further notes that “arrow-making is accompanied by great fatigue and profuse perspiration. It has a prostrating effect upon the nervous system, which shows itself again in the direction of fracture. The first fruits of the workman’s labour, while still fresh and vigorous, can be distinguished from the implements produced after he had become exhausted at his task; and it is thus noteworthy that on an unimpressible substance like flint even the moods and passions of long-forgotten centuries may be found thus traced and recorded.”