Memorial of Prof. Ridgway, geologist and mining engineer, in relation to the coal field of Rhode Island, presented to the General assembly at its January session, A. D. 1868, and printed. [electronic resource] Reprinted by order of the General assembly at its January session, 1870.
Electronic text and image data. Ann Arbor, Mich. : University of Michigan, Digital Library Initiatives, 2000. Includes both TIFF files and keyword searchable text. [Making of America] This volume is made possible by a grant from the Andrew W. Mellon Foundation as part of Making of America IV: the American voice, 1850-1877.