Obituary notices: Sir William de Wiveleslie Abney, K.C.B., D.C.L., D.Sc., F.R.S., 1843–1920; Henry Bassett, F.I.C., 1837–1920; John Cannell Cain, 1871–1921; Emile Justin Armand Gautier; William Herbert Pike, 1851–1921; John Ruffle, F.I.C., 1843–1920; Charles Simmonds, 1861–1921; Bertram James Smart, 1882–1920; Bertram Blount, 1867–1921; Alexander Wynter Blyth, 1844–1921; Sir Lazarus Fletcher, 1854–1921; David Henry Nagel, 1862–1920; William Odling, 1829–1921; Percival Spencer Umfreville Pickering, 1858–1920; John Shields, 1869–1920; Leonard Philip Wilson, 1879–1920