smaller component; the triple 35, magnitudes five, eight, and nine, distances 13", p. 61°, and 28.7", p. 124°, has for colors yellow, lilac, and blue, and the double 24, magnitudes five and six, distance 20", p. 270°, combines an orange with a lilac star, a very striking and

smaller component is lilac. The magnitudes in 12 are five and eight, distance 66", p. 168°. So also the wide double 17, magnitudes five and a half and six, distance 145", exhibits a tinge of lilac in the

beautiful contrast. We should make a sad mistake if we regarded this wonderful distribution of color among the double stars as accidental. It is manifestly expressive of their physical condition, although we can not yet decipher its exact meaning.

The binary 42 Comæ Berenicis is too close for ordinary telescopes, but it is highly interesting as an intermediate between those pairs which the telescope is able to separate and those-like B Auriga-which no magnifying power can divide, but which reveal the fact that they are double by the periodical splitting of their spectral lines. The orbit in 42 Comæ Berenicis is a very small one, so that even when the components are at their greatest distance apart they can not be separated by a five or six inch glass. Burnham, using the Lick telescope, in 1890 made the distance 07"; Hall, using the Washington telescope, in 1891 made it a trifle more than 0'5". He had measured it in 1886 as only 0′27′′. The period of revolution is believed to be about twenty-five years.

In Coma Berenices there is an outlying field of the wonderful nebulous region of Virgo, which we may explore on some future evening. But the nebulæ in Coma are very faint, and, for an amateur, hardly worth the trouble required to pick them up. The two clusters included in the map, 2752 and 3453, are bright enough to repay inspection with our largest aperture.

Although Hydra is the largest constellation in the heavens, extending about seven hours, or 105°, in right ascension, it contains comparatively few objects of interest, and most of these are in the head or western end of the constellation, which we examined during our first night at the telescope. In the central portion of Hydra, represented on map No. 7, we find its leading star a, sometimes called Alphard, or Cor Hydræ, a bright second-magnitude star that has been suspected of variability. It has a decided orange tint, and is accompanied, at a distance of 281", p. 153°, by a greenish tenth-magnitude star. Bu. 339 is a fine double, magnitudes eight and nine and a half, distance 13", p. 216°. The planetary nebula 2102 is about 1' in diameter, pale blue in color, and worth looking at, because it is brighter than most objects of its class. Tempel and Secchi have given wonderful descriptions of it, both finding multitudes of stars intermingled with nebulous matter.

For a last glimpse at celestial splendors for the night, let us turn to the rich cluster 1630, in Argo, just above the place where the stream of the Milky Way-here bright in mid-channel and shallowing toward the shores-separates into two or three currents before disappearing behind the horizon. It is by no means as brilliant as some of the star clusters we have seen, but it gains in beauty and impressiveness from the presence of one bright star that seems to captain a host of inferior luminaries.

THE UNITED STATES GEOLOGICAL SURVEY.*

BY CHARLES D. WALCOTT,

DIRECTOR OF THE SURVEY.

EOLOGY in America has advanced by steady evolution from a small beginning eighty years ago to its present proportions, where it stands as one of the great sciences of the present and of the future. The geologists of Europe founded the science of geology in the earlier years of this century, and as the tide of emigration passed across to this continent it brought with it a knowledge of science and a spirit of scientific investigation. In geology this first took systematic form in the State of New York. State after State then took up the work, and finally the Federal Government, in its western Territories. Among the men who have led in the States were William Maclure, Amos Eaton, James Hall, Ebenezer Emmons, Timothy Conrad, and their associates on the New York Survey; the brothers Rogers, and Richard Dale Owen. Jules Marcou, J. S. Newberry, and others began work in the west under the Federal Government, and following them the organizers of the first Government surveys-Clarence King, F. V. Hayden, J. W. Powell, and George M. Wheeler.

The organization of the present Geological Survey went into effect July 1, 1879, the independent surveys that had previously existed having been discontinued. It is a bureau of the Department of the Interior, and is under the immediate control of a director, who is appointed by the President and confirmed by the Senate. The members of the regular and permanent corps of the survey are nominated by the director and appointed by the Secretary of the Interior, the director making only such temporary appointments as are authorized by the secretary. A plan of operations and an estimate of the expenses of the survey are submitted annually to the secretary, to whom the director also makes report of the operations of the survey at the close of each fiscal year.

The survey occupies a rented building which has 46,480 square feet of floor space. In addition, the engraving and printing division occupies an annex building, with 8,253 square feet of floor space, and in the National Museum there are four laboratories for the preparation and study of paleontologic and paleobotanic material. Within the main building there is a chemical laboratory, in which analyses of rocks, oils, minerals, etc., are made for the geologists of the survey, as well as certain special investigations

* Presidential Address before the Geological Society of Washington, delivered December 18, 1894.

relating to problems directly affecting the study of rocks or minerals, a knowledge of which is necessary for the field geologist; a photographic laboratory, in which all negatives taken in the field are developed and prints made therefrom, and where the field topographic maps are reduced to the scale required before engraving for publication; a petrographic laboratory, which includes the necessary machinery for cutting thin sections of rocks and minerals, and for the cutting and polishing of sections of limestones, fossils, etc.

The topographic division occupies the fourth and fifth floors of the main building. This division is fully equipped with the necessary instruments for triangulation and topographic surveying. The second and third floors are occupied by the geologists of the survey, and the first floor by the administrative offices, the editorial rooms, and the library. The library at the present time contains thirty-five thousand books, fifty thousand pamphlets, and twenty-six thousand maps, all of which are intended for study and reference by the members of the survey. The administrative branch of the survey includes the chief clerk's office, the financial division, and the miscellaneous or correspondence division. In the printing division there is a full equipment for engraving, lithographing, and printing the topographic maps and folios of the survey.

The organic law of the survey, enacted in 1879, provides that "the director of the Geological Survey shall have the direction of the Geological Survey and the classification of the public lands and examination of the geological structure and mineral resources and products of the national domain." In 1882 the doubt as to the territory to be embraced by the operations of the survey was removed by the addition of the words "and to continue the preparation of a geological map of the United States." Under the directorship of Mr. Clarence King prominence was given to investigations of the mineral resources of the Rocky Mountain region in Colorado, Utah, and Nevada. A general division of mining geology was also organized, but, owing to the uncertainty of the area to be included under the term "national domain," its operations were limited to the States and Territories of the west. With the change of directorship in 1881 and the granting of authority in 1882 to complete a geological map of the United States, the policy of the survey was modified and its work was directed, under a very comprehensive plan, to the preparation of the required geologic map. This included the making of a topographic map of the entire United States as a base for the mapping of the areal geology. As adequate maps were not in existence, and areal geology without a good topographic base would be of little value, the topographic work was pushed forward; and in geology spe

cial attention was given to the consideration and solution of certain broad geologic problems presented by the wide domain of the United States. These problems embraced those of the geologic growth and development of a great continent, many of which had to be solved before the areal geographic mapping could be carried forward intelligently and with due consideration for scientific accuracy and economy. With the completion of topographic sheets, areal geology was gradually taken up, and in 1894 more than three fourths of the available geologic force was employed in areal work.

The scope of the work of the Geological Survey has thus come to include the preparation of a topographic base map of the entire United States; the study and mapping of the areal geology upon this base; the examination of the geologic structure and mineral resources of the national domain; the gathering of the statistics of mineral production; the study of the artesian and surface water supply of the United States; and, indirectly, the mineral and agricultural classification of the public lands under survey.

There is one fact that should be borne in mind when considering the scope of the work, and that is that the Geological Survey is a bureau of research. Its work is to a large extent the discovery of unknown facts and principles, and the scientific co-ordination of these and all known facts and inductions, within the scope of its work, in such a form that they shall subserve the use of both the Government and the people; the latter to include not only the farmer, prospector, miner, owner of lands, investor, and mining and civil engineer, but also the most highly trained students, teachers, and specialists.

TOPOGRAPHIC BASE MAP.-Captain George M. Wheeler said. of topographic surveys: "The topographic is the indispensable, all-important survey, being general and not special in its character, which underlies every other, including also the graphic basis of the economic and scientific examinations of the country. This has been the main or principal general survey in all civilized countries, and all other so-called surveys (as geodetic, trigonometric, etc.) are but accessories or addenda thereto. . . . The results of such a survey become the mother source whence all other physical examinations may draw their graphic sustenance." *

A recent European writer † (1892) on the general topographic maps of the present time says that all European states have undertaken uniform and continuous topographic surveys of their

* Facts regarding the Origin, Organization, etc., of Government Land and Marine Surveys of the United States. 1885. 4to pamphlet. Washington, D. C.: War Department. + C. Lowinsin Ymer. Tidskrift utgiven af Svenska Sallskapet for Antropologi och Geografi. 1891. Elfte argangen, 3e och 4e haft (slut). Stockholm: Samson & Wallin, 1892. VOL. XLVI.-35