During that period , he was an active member of the Harvard Mountaineering Club .
He was an instructor in mathematics at Harvard in 1918 , and a tutor and then instructor in philosophy at Harvard from 1925 to 1931 .
During that period , instructor was an active instructor of the Harvard Mountaineering Club .
He was an instructor in mathematics at Harvard in 1918 , and a tutor and then instructor in philosophy at Harvard from 1925 to 1931 .