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40   Life and Letters of Francis Galton

the black areas of low pressure on the barometer charts corresponding to a whole series of counter-clockwise running arrows on the wind charts; and the second half of the month marked a series of anticyclones-the red areas of high pressure on the barometric charts corresponding to a whole series of clockwise running arrows on the wind charts. About the middle of the month we have the transition from black to red areas on the barometric charts, and here sure enough are two systems of arrows on the wind charts one counterclockwise and one clockwise. But it is very clear that the broad band from the Skelligs to Konigsberg, west and east, and from Siena to Christiania, south and north, was largely inadequate to exhibit the `cores' of a cyclone and

Ga lon's Earlij Idea, of

19nfiicjelone and Ci1clone





High Barometer



Low BArometer

anticyclone on the same chart. The cores of one or other or even of both layoutside the large area for which Galton was plotting simultaneous observations. As I have already remarked, a single continent is scarcely sufficient for the study of meteorological observations. Such is one of the main lessons of the Meteorographica, and one doubts if it had been realised before that publication. Yet Galton recognised that if an observer in the northern hemisphere supposed himself standing at the core of an anticyclone-i.e. a centre of high pressureand facing towards the core of a cyclone-i.e. a centre of low pressure-the winds would pass from his left to his right hand. If we term the line of his sight a bi-cyclonic line, Galton in his Royal Society paper of December 1862