Letter from Horace T [Tabberer] Brown, 52 Nevern Square, Kensington, to [Joseph] Larmor It is time for a physicist such as Larmor to give views on the question of the ascent of sap in trees. There has been much ink on the subject but he has never given it much attention. The state of knowledge is available in Marshall Ward's 'Timber and some of its diseases'. The column of sap does not exert full hydrostatic pressure, as it is in partitions, as Larmor described. It seemed to Brown that leaf transpiration was enough to account for the result. He gives his thoughts on the lifting and osmotic pressure, including the unlikelihood of the regular pressure required by Larmor's theory. But Brown has not studied the question. 9 May 1905