Trilinear Coordinates

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. I have sought to exhibit methods rather than results, to furnish the student with the means of establishing properties for himself rather than to present him with a repertory of iso lated propositions ready proved. Thus I have not hesitated in some cases to give a variety of investigations Of the same theorem, when it seemed well so to compare different methods, and on the other hand interesting propositions have sometimes been placed among the exercises rather than inserted in the text.