The instance of the same person to Mr. Hook, for communicating his contrivance of making, with a glass of a sphere of 20 or 40 foot diameter, a telescope drawing several hundred foot; and his offer of recompensing that secret with another, teaching to measure with a telescope the distances of objects upon the Earth

In numb. 4. of these papers, pag. 67. Mr. Hook had intimated, that he would shortly discover a way of his, with a plane-convex glasse of a sphære of 20. or 40. feet diameter, without veines, and truly wrought of that figure, to make a telescope, that with a single eye-glass should draw 300, 400, yea 1000 feet, without at all altering the convexity: Monsieur Auzout returns this consideration, and offer upon it, which follows: