Tip: Pearl would use a scale!
Pearl I. Young, the NACA’s first female professional, at work in the instrument research laboratory circa 1929. Photograph published in Winds of Change, 75th Anniversary NASA publication, by James Schultz, page 47. Also published in Engineer in Charge: A History of the Langley Aeronautical Laboratory, 1917-1958 by James R. Hansen, (page 209).