Image: ‘The Falls of the Rhine at Schaffhausen’ by J. M. W. Turner. Undated. Pencil, red ink, and watercolour on paper. “Once as we descended a mountain side by side with the mountain torrent, my companion saw, while I missed seeing, a foambow.” A what?, I asked the page, a foambow? Clearly Christina Rossetti knows about foambows, even if she has never seen a foambow. The OED lists its first use in ‘Oenone’ by Alfred Lord Tennyson in 1832: “And his cheek brighten'd as the foam-bow brightens.” While Rossetti uses the word in the entry in her daily devotional ‘Time Flies’ (published 1885) for September 16, continuing: “In all my life I do not recollect to have seen one, except perhaps in artificial fountains; but such general omission seems a matter of course, and therefore simply a matter of indifference. That single natural foambow which I might have beheld and espied not, is the one to which may attach a tinge of regret; because, in a certain sense, it depended u...