330-PS-2497 (USN 708510):  The spiral vane which produces a whirling motion in a new vortex thermometer, permitting correct measurement of air temperatures in aircraft flying at speeds up to 500 miles per hour, is pointed out to Commander F.P. Anderson by Mr. R.E. Ruskin, of the Naval Research Laboratory.  Lowered pressure at the center of this vortex produces a cooling effect that offsets the heating effect produced on the surrounding air by the plane’s flight.   Photograph released February 1, 1952.  (5/26/2015).
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