Note 2735 — PORTUS ITIUS

Airy seems to have felt the necessity of bolstering up his argument; for he remarks (Essays on the Invasion of Britain, &c., p. 27) that ‘before the Triangulation of the year 1787, it was a fair and an insoluble question, whether the distance from the Continent to Britain was less than twenty or greater than forty miles’. Perhaps; but long before the aforesaid Triangulation sailors used to make wonderfully good guesses about this ‘insoluble question’. Cluver tells us that while staying with Sir Thomas Waller, Warden of the Cinque Ports, he questioned all who could give him trustworthy information, and particularly seamen, as to the passages between England and France. The unanimous reply was that the distance between Dover and Calais was 28 English miles, and that the most convenient passage was between Dover and Boulogne, and was 32 English miles (Germania antiqua, 1631, lib. ii, cap. xxviii, p. 445). Similarly, the Arab geographer, Edrisi, who died about 1180, affirmed that the distance between Wissant and England was 25 Roman miles (Geogr. Nubiensis ..., 1619, pp. 253-4).