Paper, 'On curves circumscribing rotating polygons with reference to the shape of drilled holes' by A [Arnulph] Mallock Mallock writes: 'It is well known that drills and other tools of the same class which are guided by their cutting edges tend to, or at any rate can produce holes which are not circular in section, and further, that if the tool have n equidistant edges, the hole which it produces, if not circular in section, will have n+1 sides or similar arcs,* but the exact shape of these holes and the limits to their possible departure from circularity have not as far as I am aware been hitherto examined.' Annotations in pencil and ink. Subject: Engineering Received 11 June 1883. Read 21 June 1883. Communicated by Lord Rayleigh [John William Strutt]. A version of this paper was published in volume 35 of the Proceedings of the Royal Society as 'On curves circumscribing rotating polygons with reference to the shape of drilled holes'. 1883