Note 62 — COLOURS and COLOURING.

Although the author seems to have designed that this, and many other propositions to which he refers, should have formed a part of some regular work, and he has accordingly referred to them whenever he has mentioned them, by their intended numerical situation in that work, whatever it might be, it does not appear that he ever carried this design into execution. There are, however, several chapters in the present work, viz. ccxciii. cclxxxix. cclxxxv. ccxcv. in which the principle in the text is recognised, and which probably would have been transferred into the projected treatise, if he had ever drawn it up.