and the causes and remedies for the inevitable conflict that arises from the spread of civilization over a region previously inhabited by savages. I may be allowed to express the hope that our labors in this direction will not be void of such useful results.

FIELD SEASON OF 1877.

About the middle of May last the surveying corps again took the field. This year the rendezvous camp was at Mount Pleasant, a little town in Utah about 125 miles south of Salt Lake City. Three parties were organized under the direction of Professor Thompson, one to extend the triangulation and two for topographic purposes.

In the early part of the season, the field work was somewhat delayed by reason of the late falling of snow, making it impracticable to ascend the higher mountains.

The area designated for the season work lies between 38° and 40° 30′ north latitude, and between 109° 30′ and 1120 west longitude, Greenwich, and is embraced in atlas sheets 86 and 75.

TRIANGULATION BY PROFESSOR THOMPSON.

The triangulation party was under the immediate charge of Professor Thompson, assisted by Mr. O. D. Wheeler. In the early part of the season the work was extended over a broad area west of the Green River.

On account of general rumors for a number of years concerning the hostility of the Ute Indians in the vicinity of the Sierra la Sal, on the east side of the Green and Colorado Rivers, he deemed it wise to consolidate his party with one of the topographic parties, for the purpose of visiting that region, in order that he might have a force of greater strength. For this purpose he took with him the party under Mr. Graves, and the triangulation and topography were carried on simultaneously. Events proved that the rumors were groundless.

The triangulation was extended over an area of something more than 16,000 square miles. As in previous years the work rests on the baselines of Kanab and Gunnison and was connected on the east with the triangulation-points established by Dr. Hayden, in charge of the United States Geological Survey of the Territories, and on the north with those of Clarence King, United States Geologist in charge of the Survey of the Fortieth Parallel. The instrument used was the same as that of the former year; the triangulation-points were artificial, marked by by stone cairns and flag-staffs.

Professor Thompson also determined the amount of water flowing in the larger streams of the region.

TOPOGRAPHIC WORK BY MR. GRAVES.

The district assigned Mr. Graves for topographic work was the eastern half of atlas sheet 75 and that portion of sheet 86 lying east of the Green and Colorado Rivers-an area of about 10,000 square miles.

The most remarkable topographic feature of this region is a bold escarpment facing the south and extending from the western far beyond the eastern limit of Mr. Graves' work. This is known as the Book Cliffs. At the foot of this escarpment lies a narrow valley through which passes the only practicable route of travel between Central Utah and Western Colorado. South of the valley the whole region is cut by a labyrinth of cañons, formed by the Grand, Green, and San

Rafael Rivers and their tributaries. This region is one of the most inhospitable and inaccessible in the territory of the United States. It is characterized by extreme aridity, and some portions are cut by many narrow gorges, forming "alcove lands." In other portions are found hills of naked sands and clays-regions of bad lands. Bold cliffs, towering monuments, hills of drifting glittering sands, and deep tortuous cañons give to the landscape an appearance strange and weird.

The Book Cliffs rise to an altitude above their base of 2,000 feet, and about 8,500 feet above the sea-level, and the country from the southern crest inclines gently northward to the valleys of the White and Uinta Rivers. This gigantic terrace, called the Ta-vá-puts Plateau, is cut in twain from north to south by the profound gorges of the Green River, known as the Cañon of Desolation and Gray Cañon. The drainage of the plateau is northward from the brink of the cliffs through deep narrow cañons for many miles, but at last all these enter the Cañon of Desolation a few miles from its head. North of the Ta-vá-puts Plateau are the valleys of the White and Uinta Rivers. Nearly all the former and a large portion of the lower course of the latter are within the boundaries of Mr. Graves's work.

Over the whole district assigned to Mr. Graves he extended the secondary triangulation. Owing to the peculiar topography of the country, bis stations will average about ten miles apart. He also made a connected plane-table map of the whole area, aud complemented his work with orographic sketches.

In the southern portion of the area surveyed by Mr. Graves consid erable bodies of irrigable lands are found along the Grand, Green, San Rafael, and Price Rivers; and in the northern part, along the Green River and in the valleys of the Uinta aud White Rivers, are large tracts of excellent land, on which the waters of the streams named can be conveyed at slight cost. Mr. Graves paid especial attention to the extent and character of these lands, and to the amount of water carried by the streams.

On the Ta-vá puts Plateau are small forests of pine and fir, but generally Mr. Graves's district possesses no more timber than sufficient to meet the future local requirements of actual settlers.

TOPOGRAPHIC WORK BY MR. RENSHAWE.

The district assigned Mr. Renshawe was the western portion of atlas sheet 75, an area of about 6,000 square miles. The eastern portion of this area is a broad plateau, having an average elevation of about 9,500 feet, cut by deep valleys and drained from its very western edge toward the east by the Dirty Devil, San Rafael, Price, and Uinta Rivers. The western portion includes broad valleys, abrupt ranges of mountains, and one plateau of considerable extent. The principal valleys are the San Pete, Juab, and Uinta, all having a general northern and southern trend and an average elevation of about 5,000 feet, and all drained by the San Pete River and the streams flowing into Utah Lake. The mountain-ranges standing between the valleys are the Wasatch, rising in its highest peaks to 12,000 feet, the Cañon Range, and the Valley Range, each reaching an altitude of nearly 10,000 feet.

The plateau, which we have called Gunnison Plateau, has an area of about 750 square miles, and an average elevation of 8,000 feet. It is bounded on three sides by almost vertical walls, and is extremely rugged and difficult to traverse.

There is but little irrigable land in the eastern portion of Mr. Renshawe's district, but the broad valleys of the western portion contain

large areas of excellent lands, and the numerous streams furnish a good supply of water.

On the plateaus and mountain ranges are large quantities of excellent timber.

On the headwaters of Price River and on Huntington Creek are extensive beds of coal, and on that portion of the Wasatch Range included in Mr. Renshawe's district are deposits of silver and galena.

Mr. Renshawe extended the secondary triangulation over the whole district assigned him, making stations at an average distance of about ten miles, and measuring all the angles of nearly every triangle in the extension. He also made a connected plane table map of the whole area, and complemented his work with a complete set of orographic sketches.

The season's work has further demonstrated the value of the orograph and plane-table, and the practical experience has shown them to be well adapted alike to regions of mountains, hills, valleys, plains, and plateaus.

The hypsometric work of this season rests on a primary base established at the general supply and rendezvous camp at Mount Pleasant, and connected by a long series of observations with the station of the United States Signal Service at Salt Lake City. At the base station observations were made with mercurial barometers four times each day, and for eight days during the month hourly from 7 a. m. to 9 p. m. Mercurial barometers were carried by each field party, and observations made to connect every camp with the base station. All the geodetic points and topographic stations were connected by observations with mercurial barometers either with the camps or directly with the base station, or both. All the topographic stations were also connected with each other by angulation, and from these stations the altitudes of all located points were determined by the same method.

The hypsometric work is of the greatest importance, having a direct and practical value in the classification of the lands and the determination of the best methods of utilizing the waters of the streams for irrigation. On account of its practical utility to the agricultural industries of the country, it is believed that more thorough methods should be adopted, and for this purpose it is suggested that a hypsometric baseline be established, extending across the continent, or at least from Lake Michigan to the Pacific Ocean. The railroad lines are now used for this purpose, but their methods of leveling are not deemed of sufficient accuracy for the wants of the work. More refined instruments should be used, more careful work should be done, and the subject should receive careful and thorough discussion. From the base line thus estab lished, lateral lines should be run to the base stations used for each field season by like refined methods.

It is believed that another improvement in this work could be made by the preparation of new tables based upon series of observations made in that portion of the United States where these surveys are couducted. The hypsometric tables now in use are based on observations made at Geneva and Saint Bernard, in Switzerland, points about sixty miles apart, and under climatic conditions greatly different from those obtaining in the Rocky Mountain Region. For this purpose it would be necessary to occupy one or more elevated mountain peaks, with corresponding stations at or near the base, and record hourly observations through a period of one or more years. These stations should be cou

nected by careful leveling, and also connected with the base line above mentioned. The Rocky Mountain Region affords localities better adapted to this purpose than those used in the construction of the present tables.

CARTOGRAPHY.

Much attention has been given to this subject for the purpose of determining the best methods of representing the topography of the region surveyed, taking into consideration the character of the country, the more important facts to be embodied, and the scale adopted for the physical atlas of the Interior Department. The system of cartography in use in this country and many of those in Europe have been examined and studied, and many experiments have been made in the office for the purpose of determining the best methods adapted to these circum stances and conditions. Some of these experiments being now inchoate, it is proposed at some future day to give a full account. of the same, together with the results reached.

CLASSIFICATION OF LANDS BY MR. GILBERT.

The geographical and geological survey under my direction has been extended over the northern portion of Arizona and the greater part of Utah, but a broad strip along the northern end of the latter Territory was embraced in the survey made by Mr. Clarence King under the War Department. It seemed desirable however to extend the classification of lands over this latter region, and this duty was assigned to Mr. Gilbert.

Mr. Gilbert took the field at Salt Lake City and traversed all of the Territory lying west, north, and northeast of that point, a tract comprising so much of the drainage basin of Great Salt Lake as lies in Utah. In this area is included the most valuable portion of the Territory, as well as one of the most sterile. A very small part of it will repay cultivation without irrigation, but this is exceptional, and in general the possibility of agriculture depends on the possibility of artificial watering. The Bear River and the Jordan carry as much water as can profitably be used upon all the lands to which it is practicable to convey them by canals, and those lands were measured in order to determine the agricultural capacities of the river valleys. The smaller streams, on the contrary, are inadequate to serve the arable lands through which they severally run, and the agricultural capacities of their valleys were ascertained by measuring the volume of each stream. East of Great Salt Lake are great mountain ranges, the Wasatch and the Uinta, and large streams flow from their melting snows all through the summer season. The Bear, the Weber, and the Jordan flow to the lake, and the three rivers can be made to reclaim 800,000 acres of land in their valleys. This is 12 per cent. of the district which they drain. West of the lake the plains are interrupted by mountains, but there are none of magnitude; the snows of winter are dissipated too early in the spring to be of use for irrigation, and much of the land is an absolute desert. In a total area of 8,300,000 acres only 21,000 acres are of value for farming-one-fourth of one per cent.

These estimates are based upon the experience of the farmers of the district, who have practiced irrigation for thirty years and have given it a greater development than can be found elsewhere in the United States. They have now under cultivation a third part of the irrigable lands of the Salt Lake Basin, and are utilizing many of the small streams to the full extent of their capacities. A careful study was made of their oper

ations for the purpose of learning the quantity of water necessary to redeem a given quantity of land under various conditions of soil and climate, and the resulting determinations were used in computing the areas susceptible of irrigation by the streams and parts of streams that are still unused. The greater part of the future extension of the cultivated areas will be accomplished only by expensive engineering works, including the damming of the principal rivers and the construction of long canals. Five million dollars is probably a moderate esti mate of the cost of redeeming the 500,000 acres that are susceptible of reclamation, and the requisite capital will have to be concentrated upon a small number of large canals.

An investigation was also made of the climate of the district as recorded in the rise and fall of Great Salt Lake. The lake, having no outlet, is filled to higher levels in moist years and shrinks again in dry. No systematic record of its fluctuations has been kept until quite recently, but for the past thirty years the interests and pursuits of settlers upon the shore have been more or less affected by them, and it has proved practicable by gathering the evidence scattered among citizens to elicit the history of the changes. From the year 1847 to the year 1850 the water was constantly at a low stage. A series of five moist seasons then raised its level nearly five feet, and a succeeding series of dry seasous again depressed it, until in 1861 and in 1862 it was as low as when first observed. From that time until 1868 the water rose step by step to its present level, and it has since then continued about ten feet higher than in 1850. About four feet below the present surface there was a beach mark which the lake had not previously cov ered for many years, or perhaps for centuries, so that the present condition must be regarded as decidedly novel and exceptional. The area of the lake is much greater at its high stage than at its low, and the evaporation from its surface is correspondingly increased. To maintain its present level the inflowing water must be a tenth part greater in amount than it formerly was; and that it is greater is universally testified by those who use the tributary streams for the purpose of irrigation. Whether this increase of streams is due to a transient variation of climate or to the modifications wrought by man upon the face of the country is a question not yet decided; but it may well be doubted whether the agriculturists of Utah should anticipate for the future a climate so favorable as that of the past ten years.

To facilitate the record of the future fluctuations of the lake a number of monuments have been established. At the suggestion of Prof. Joseph Henry, a graduated pillar was placed at the water's edge in 1875 by residents of the Territory, and observations were continued for more than a year. The locality selected has however become inconvenient, and Mr. Gilbert has this year erected a second pillar at a more accessible place. He has moreover established near each of the graduated pillars a permanent stone monument, placed so far above the water as to be in no danger of disturbance by the waves, and these have been connected by spirit-level with the surface of the lake, so as to serve as permanent future reference points.

Mr. Gilbert gave attention also to the timber lands of the same district, investigating their character and extent. They are confined to the higher altitudes, and they form no continuous body of great extent but are scattered in small patches here and there among the mountains.

It will be seen that Mr. Gilbert in performing the special work to which he was assigned, namely, the classification of the lands, has also extended his researches into a broader field embracing climatic changes.