The investigation given in the following Note was suggested by a passage in the paper by Mr Leraoine, presented to the Society by Dr. Mackay at a recent meeting. The main subject of that paper is what he terms the “Transformation continue dans le triangle et dans le tètraédre”; for the explanation of that phrase and other terms connected with it, the reader is referred to the paper just mentioned. In the notation for the quantities connected with the triangle, however, I shall follow Dr. Mackay''s system as explained in his paper in Vol. I. of our Proceedings.