British gustiness meter

The Caltech machine shop built a few British gustiness meters, which was a wind vane free to move up and down as well as left-to-right. It had a Light-weight ink pen on its downwind side, which put ink marks on a sheet of curved paper. We let it operate for two minutes, and the pattern of scribbles indicated the degree of horizontal and vertical turbulence. 

Under the range of wind speeds and temperature gradients available in Florida, we compared, side by side, our gustiness meter with the British bivane in the Bushnell meadows and forest. Also we made these comparisons at Rosamond Dry Lake. At all of these sites and with large scatter of points, we found that standard vertical width of the bivane record multiplied by the numerical factor of 0.23 was equal to our measured vertical gustiness ... 

Our gustiness meter measured the angle of the vertical displacement from the horizontal. The British bivane measured the full width of the vertical ink tracings, which is twice the upward directed component that we used, and the bivane was smaller and had a much shorter length from vane to swivel point than our instrument. These two features explained why the readings of the two gustiness meters differed by a constant value. For the rest of this chapter, I write within parentheses the British bivane measurements multiplied by the factor 0.23 for measurements not made by our group. 

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