"The author of this publication being a man of leisure, and living in a retired situation, remote from any opportunity of conversation with mathematicians, would be extremely glad of a correspondence with any such, who are willing to be at the expense of the same; or if this be thought too much, will pay the postage of his answers to their letters. But no letters, except post-paid, can be received by him; otherwise a door would be opened for frolic, imposition, and impertinence. Any new geometrical propositions, either theorems or problems, would be received with gratitude, and if sent without solutions, he would use his best endeavours to return such as might be satisfactory. Any new solutions of propositions already in print, _especially of those included in the present collection_, would also be very agreeable. If a variety of such demonstrations essentially different from those of the original authors should be communicated, he proposes at some future time to publish them all, with a fresh collection for further exercise; and then each author's name shall be affixt to his own solution, or any other signature which he shall please to direct. Any person who shall favor the publisher with his correspondence shall have speedily conveyed to him the solutions of any propositions contained in this collection, which he may be desirous of seeing. Letters (post-paid) directed for P. Q., to be left at Mr. Nourse's, Bookseller, in the {527} Strand, London, will be carefully transmitted on the first day of each month, and all correspondents may expect answers during the course of that month."