Paper, 'On the formation of ripple-mark in sand' by G H [George Howard] Darwin Darwin writes: 'The following paper contains an account of experiments and observations on the formation of ripple-mark in sand. The first section is devoted to experiments on the general conditions under which ripple-mark is formed, and especially on the mode of formation and maintenance of irregular ripples by currents. In the second section it is shown that regular ripple-mark in sand is due to a complex arrangement of vortices in oscillating water; and the last section gives some account of the views of certain recent observers in this field, and a discussion of some phenomena in the vortex motion of air and water.' Annotations in ink. Includes 21 pages of prints and drawings of ripple marks. Subject: Mineralogy Received 18 October 1883. Read 22 November 1883. A version of this paper was published in volume 36 of the Proceedings of the Royal Society as 'On the formation of ripple-mark in sand'. 1883