Sleep and the Immune System, Measuring Carbon, Specimens of Hair. Feb 1, 2019, Part 2 Listen Download Embed Share Share this on Facebook (Opens in a new window) Share this on Twitter (Opens in a new window) Share this via Email A hair sample of George Washington, from Peter A. Browne's hair collection in the book "Specimens of Hair." ( Photographs by Rosamond Purcell, courtesy of Blast Books. ) Hosted by John Dankosky Produced by Science Friday and WNYC Studios