WEDGE. (from the Danish wep•e.) Writers on mechanics, in treating of the Wedge, have frequently drawn false inclu sions respecting the proportion which exists between the impelling power applied to the head, and the resisting powers opposed to the sides; and those conclusions have resulted from false opinions concerning the directions of the resisting powers.
It is evident, that when wood or other is split by a wedge which does not fill the cleft, that is. When the angle Or the cleft is more acute than that of the wetr•, the power or action of each side of the wedge, equal and opposite to the resistance of the cleft, must be resolved into two; the one in the direction of the side of the cleft, which tends to thrust it forward ; and the other perpendicular to that direction, whi•h tends to tear it asunder. It is by not attending to the above solution, that writers on this subject, have been led into mistakes; for, instead of considering the powers which act in those two directions, they have imagined a single power only as acting obliopiely on each side. But it' the sides of
the wedge are perfectly polished, as we must here consider them, no single permanent power can be applied to impel any one of them, unless its direction be perpendicular to I he plane of the side to which it is applied ; therefore., two oblique powers, applied on opposite sides of the same point, are at least necessary to sustain each other and the action of the plane ; and in the ease of the wedge above mentioned, the directions of those two oblique powers will always be perpendicular to each other, as will appear obvious from the two tiollowing