WIND PRESSURES.

Ashburton Guardian, Volume XXiX, Issue 7727, 22 February 1909, Page 1

WIND PRESSURES.

In studying the pressure of the wind on the huge Forth Bridge nearly a quarter of a century ago, Baker, the <n-eat English engineer 1, discovered that the prepare on large surfaces was relatively less than on small ones., Ims has remained unexplained until the recent experiments of T. E. Stanton at the National Physical Laboratory in England. Stanton finds that, when the wind blows against any large obstacle its intensity is unevenly distributed, and that the lower pressure on large surfaces is due to what may be called the "structure" of tho wind, whose gusts are more effective on the small areas than on large ones. Owing to tliis " gustiness " of the wind, tests made in laboratories with steady af-. tificial currents are misleading. = The resistance offered by a structurip to a natural air current in the open is 1? to 20 per cent greater than thatjj offered to an artificial " wind" in a laboratory test. The experiment oh f which Stanton relies for his conclusions were mad© on flat surfaces ranging up to a hundred square feet, exposed io : actual winds in open air.