Letter from Thomas Ralph Merton, on a paper 'The production of diffraction gratings. II. The generation of helical rulings and the preparation of place gratings therefrom' by R G N Hall and L A Sayce, to John Courtney Graddon Paper reference code: A150 Merton remarks the previous paper in this series was sent to him to referee, therefore if it is required to send him this paper it is not needed as he has already examined the content. Written at Subbings House, Maidenhead Thicket, Berkshire [England]. [Published in Proceedings A, 1952]. Endorsed on recto as received 16 August 1952. 15 August 1952