National Geographic : 1898 Nov
468 WHAT IS THE TIDE OF THE OPEN ATLANTIC? say when the idea of deriving tides from this southern ocean arose. Lieut. J. Cook, reporting tidal observations for the south Pacific, asserted, in 1772,* " I am fully convinced that the flood comes from the southward, or rather from the southeast." Laplace seems to have entertained a similar idea for the Atlantic, and assigned a day and a half as the time it took a wave to come from the " main ocean.' The earliest attempt to draw cotidal lines was in 1807, by Dr Thomas Young.t It is a sketch of the British islands, with coasts FIGURE 1 of France and Norway and progressive tidal lines. The lines were drawn straight, crossing the English channel nearly at right angles to its axis, and in other places springing squarely off from the shores. In a supplement to the Encyclopaedia Britannica, written in 1823, Dr Young suggested the tracing of cotidal lines, indicated sources of data, declared the scheme impracticable, but collected and reduced the data for 150 stations, and described *Phil. Trans., 1772, p. 357. t Lectures on Natural Philosophy, vol. i, pl. xxxviii.