The diagram outlines the Trisector as in the position in which the angle B A L, which may be any angle of less than 225°, is by its aid divided into five equal angles.

That instrument was described to this Society in a communication submitted to them on the 4th of November last. It consists of two pieces, A I F D and BHG. Those pieces are conjoined, as the blades of a pair of scissors are, by a small cylindrical pin inserted in a small cylindrical hole at C in each of them, which it fits, and round which they may turn.