Revere, MA: 12-17-2011: Bundled against the cold, Zach Donahue (cq) is comfortable in his beach chair as he uses electrical resistance to test the water content of the sand at Revere Beach in Revere, Mass. Dec. 17, 2011. Donahue, who is from Medford and is a graduate student at Tufts, was working on the project for a geophysics class he's taking at Boston College. Donahue anticipated the water content would rise with the rising tide. photo/John Blanding, Boston Globe staff story/ , ( feature )