The rational meaning of ‘surd’
Lewis Carroll, in his Phantasmagoria, and Other Poems (1869), constructed a poem that yielded a double acrostic, with the first and last letters of 13 words that were suggested by the 13 stanzas spelling out ‘quasi-insanity commemoration’, a reference to an Oxford commemoration ball. The first stanza, which yields the word quadratic, goes: ‘Yet what are all such gaieties to me/ Whose thoughts are full of indices and surds? x2 + 7x + 53 = 11 / 3.’ What, though, is the solution to the equation? I have seen it said that there is none, unless a minus sign is placed before the 53. But then it wouldn’t scan, and Lewis Carroll liked regular scansion: 11 / 3 is to be pronounced ‘eleven thirds’, not ‘eleven over three’.
