As a result of their isolation, the proportion of endemic plants is greater here than in any other region, and the great elevation of the mountains, with the consequent variation in temperature, moisture and barometric pressure, has multiplied the number of species.
The regular tides are hardly perceptible, but, under the influence of barometric pressure and wind, the sea-level occasionally varies as much as ft.
(9) The velocity then should be independent of the barometric pressure, a result confirmed by observation.
The theoretical investigation given above shows that if U is the velocity in air at 1° C. then the velocity U ° at o° C. in the same air is independent of the barometric pressure and that Uo = U /(1 +o o01841), whence U 0 =332 met./sec.
The average barometric pressure over England is about 2 9.94 in., and normally diminishes from south-west to north-east at all seasons, the mean pressure on the south coast being 29.97 and that on the northern border 29.88.