DILLER, Joseph Silas, geologist, born in Plainfield, Pennsylvania, 27 August 1850. He was graduated at Lawrence scientific school of Harvard in 1879, and spent two years in postgraduate studies at Harvard and at the University in GSttingen. From 1873 till 1877 he taught in the State normal school in Westfield, Massachusetts, and from 1881 till 1883 was geologist of the Assos expedition. In 1883 he became assistant geologist on the U. S. geological survey, and in that capacity has traveled extensively throughout the United States. He is a member of several scientific societies, and author of numerous papers that have been published in scientific journals in the United States and in Europe, the principal of which are "Notes on the Geology of the Troad" (1883); "Diamonds in the United States" (1886) • and "Notes on the Geology of Northern California" (1886).