Letter and paper from Robert S [Stawell] Ball, Observatory, Cambridge, to 'My dear Master' [Joseph Larmor] Brief covering note: 'The enclosed is but a trifle but it may interest you for a moment unless, as is quite probable, you are well acquainted with it'. With a short paper, including diagrams, 'On a representation of the diameters of a conic by points on a circle'. 15 July 1908