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Show 8 on in the field, as the long field- seasons have permitted the accumulation of more data by the topographers than could possibly be properly reduced to the finished map during the office- season. Their labors wjll place in shape for the lithographer four, if not five, of the atlas sheets for early presentation, and the material will be reduced to the atlas form, thus giving a clear and practical idea of what may be expected from a continuation of the mapping- work. The areas to be entered and examined, especially the southern portion, prior to the close of the season already begun, as may be readily noted by examining the accompanying map, are far away from railroads, other routes of communication, and telegraph lines, in regions where points of supply are not easily accessible. Labors in this field become exploration indeed, and hardship, fatigue, with now and then scarcity of supplies and danger from hostile Indians, fall to the lot of those who are chosen for the task; and when the history of explorations and surveys within our borders, past, present, and future, becomes a subject upon which more light is thrown, then will come a truer appreciation of what is comprehended by leaving tbe highways of the mountain, valley, and desert plain, to search out the physical details of almost inaccessible altitudes, or the extent and structure of arid plains and sanxly deserts, stretching in endless configuration, westward, from the Mississippi to the Pacific. METEOROLOGY. The meteorological data already accumulated by the survey is very great, consisting of extended series of hourly observations at the main astronomical stations, and at certain others along the routes followed, with the general barometric record for altitudes, numerous aneroid profiles, & c. From this mass all that is worthy of publication will be segregated, and this matter, together with the plates from the hourly series, will form the subject for the meteorological volume, or No. 3 of the series. Lieutenant Hoxie has been charged, while in the office, witlj the reduction of these observations, and now, while in the field, one computer is kept employed in carrying forward the work. The instructions for this season have systematized still more these observations, throwing out all superfluous ones, having in view a result productive of the most good with the least expenditure. Tbe accumulation of valuable data in this department will this season be much in advance of other years. GEOLOGY. Examinations in this branch have been intrusted to civil assistants, and their reports, now well advanced, will attest their greater or less skill and success in combining the features presented by nature into a sequence of geological facts. The season of 1872 offered greater facilities for carrying ou the work of observation; and this season, it may be said that the system fairly elaborates, for the greater part, into a geological survey, instead of a reconnoissance. Reports for 1871 and 1872, from three of the geological assistants, Messrs. Gilbert, Marvine, and Howell, will furnish the material for volume No. 4 of the series. The reports by knowh scientists upon the invertebrate fossils, for 1871,72, and ' 73, and the vertebrates, for 1872 and ' 73, will be grouped with the plates of the new species, and accomplish data for volume No. 5. |