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Show 103 • 2d. The tables of altitudes, with general description of the locality of each group. 3d. Contour- maps of the atlas- sheets, with the curves at such intervals of altitude as are warranted by the results in barometric hypsome-try, in conjunction with the elevations and vertical distances determined by the topographers. 4th. Tables and plates deduced from the hourly observations at the astronomical stations. These will comprise the abnormal and horary oscillations, and the changes iu temperature and humidity of the atmosphere, with their effect upon the mercurial column. With these will be published all facts that have been observed concerning the climate and climatal oscillations, with a description of the physical geography of the region of territory surveyed. This branch of the survey is indebted to the cordial co- operation of the United States Signal- Service. It has not been practicable, with the limited force that could be employed in working up the meteorological observations, to prepare this matter for publication; but, as time can be spared from other branches, this will gradually be brought forward. Being an auxiliary to the other branches of the survey, it is in all respects subordinate to, and most of its results incorporated with, them. GEOLOGICAL BRANCH. Four professional geologists have, for different periods, been employed to accompany the several geographical parties and examine the structure of the region traversed. Of these, Mr. G « K. Gilbert was engaged in 1871, and has continued with the survey up to the present time; Mr. A. B. Marviue was employed during a portion of the first year only; Mr. E. E. Howell during the second and third, and Prof. J. J. Stevenson during the third year. In 1871, Mr. Gilbert traveled mostly with the main field- party, crossing portions of Nevada, California, and Arizona, and making the voyage of the Colorado. Mr. Marvine, who spent but two months at geological work, began his observations at St. George, Utah, and continued them, via Prescott, Camps Yerde, and Apache, to Tucson, Ariz. the succeeding year, Messrs. Gilbert and Howell were employed principally in Western and Southern Utah; but their examinations also reached into Eastern Nevada and Northern Arizona. For the greater portion of the season Mr. Gilbert accompanied Lieutenant Hoxie, and Mr. Howell the main division; but, upon the return - march, Mr. Howell joined Lieutenant Hoxie's party, while Mr. Gilbert was detached, and traveled alone by way of the valley of the Sevier to the final rendezvous at Salt Lake City. In 1873, Mr. Howell accompanied Lieutenant Hoxie throughout the season, spending the earlier portion of it in Southern Central Utah, and the latter in Western New Mexico; Mr. Gilbert traveling with divisions of the main party in New Mexico and Eastern Arizona, and Professor Stevenson with the party commanded by Lieutenant Marshall in Colorado. In all cases the geologists were assigned to separate topographical parties, and their routes arranged, so as to give them opportunity to acquire the most comprehensive ideas of the character of the country, and to obtain the fullest collection of data in a little- known region. To get a right understanding of the results of their work, it is necessary to appreciate a broad distinction that exists between two regions |
