Resumen de Letters.

Jack W. Hakala, David Reid, Azzam Qasrawi, Syd France, Dennis Coleman, Mary Ellen Clark

• Several letters to the editor and replies are presented in response to articles in the November 2015 issue including "Seeing in the Dark," by Joshua Frieman, "Disease Detector," by Shana O. Kelley, and "Where Is Here?," by George Musser.