Letter from W H [William Henry] Bragg, Great Northern Hotel, King's Cross Station, London, to [Joseph] Larmor Bragg did not hear Larmor's paper at Hull, since he had to give one himself, but Rankine gave him a copy of it. Some work at University College bears on the subject: Astbury has solved the structure of tartaric acid, which he describes with a sketch, and notes how the information was obtained, including from chemical formula showing linkages. The molecule shows two twists in opposite directions: one is molecular, the other is caused by the crystalline structure only. It seems likely that this would account for the anomalous optical activity of tartaric acid. n.d. [1922?]