The title of the sketchbook refers to a series of studies of boats in ice; ff.10, 12, 14 show small boats apparently on the frozen Thames; ff.15, 16, 17, 18 are presumably imaginary scenes of pack-ice with sailing vessels caught in it. A famous frost on the Thames was that of January 1814, and it is possible that the sketchbook dates from that time; but there is no strong evidence to contradict Finberg's dating of c.1806-8.