FORE:We have assumed in our last remark that it is possible to discover some sort of chronological order in the Platonic Dialogues, and to trace a certain progressive modification in the general tenor of their teaching from first to last. But here also the positive evidence is very scanty, and a variety of conflicting theories have been propounded by eminent scholars. Where so much is left to conjecture, the best that can be said for any hypothesis is that it explains the facts according to known laws of thought. It will be for the reader to judge whether our own attempt to trace the gradual evolution of Platos system satisfies this condition. In making it we shall take as a basis the arrangement adopted by Prof. Jowett, with some reservations hereafter to be specified.A common angular-pointed drill is capable of withstanding a greater amount of strain upon its edges, and rougher use than any other cutting implement employed in machine fitting. The rigid support which the edges receive, and the tendency to press them to the centre, instead of to tear them away as with other tools, allows drills to be used when they are imperfectly shaped, improperly tempered, and even when the cutting edges are of unequal length.