The report on the Rock Waters of Ohio concerns, first, those waters, chiefly in the northwestern and western part of the State, that are obtained from a considerable depth as compared with ordinary wells, the knowledge of which was almost wholly derived from wells drilled in the search for oil and gas, and was necessarily fragmentary and incomplete; because water was not included among the objects of search, but was considered a hindrance and obstruction to be got out of the way as well as possible; and, second, flowing wells, including only those having considerable head of pressure and those occurring in considerable areas, all of which belong entirely to the drift. Further, a brief review is given of some facts of unusual interest that were developed in the deep drillings concerning the preglacial drainage system of the part of the State in question. Indications of old river channels, one of which seems to have been extensive, were found at several points. Among the curious results of these studies was the conclusion, "seeming to be already established," "that the Ohio River, as we now know the stream, is of recent origin, and that the main volume of water gathered in it at the present time originally flowed across the State to the northward at least as far as Auglaize and Mercer Counties, where it turned to the westward toward the present lines of Wabash drainage in Indiana." Professor Orton seems to have placed considerable emphasis on the value of a study of the rocky floor of the State, concerning which all we know at present is derived from the revelations of deep drillings at haphazard; and he thought it would be a good work for the State to make use of all accessible data of this kind at once in constructing a model of the rocky floor of the region under review. The care and fidelity with which he studied the underground geology are exemplified in a map attached to the paper on the oil and gas fields, in which the horizons of the Trenton limestone are indicated and approximately bounded as they occur by gradations ranging from fifty to two hundred and fifty feet, from elevations above the ocean level to one thousand and more feet below. Another contribution of Professor Orton's which may appropriately be given special notice is his part of the article on Ohio in the Encyclopædia Britannica, in which a succinct, clear, and comprehensive account of the geology of the whole State is given, with its salient features delineated so sharply that one may almost conceive from it a definite geological picture of the region. Of all his scientific work, however, Professor Orton regarded the fixing of the order of the coal measures of Ohio as the most important; and he considered the determination of the order of the subcarboniferous strata, and particularly of the Berea Grit, as constituting a large permanent service to the study of the geology of the State.