better with the natives than with the Arabs; for whilst the former regard all rivers flowing, as we do, from head to mouth, the Arab invariably says it runs from mouth to head. In a southerly direction the Uaganda boatmen go as far as the island of Ukerewé, which I saw on my first journey to Muanzae, the southern extremity of the lake; and to the eastward beyond the escape of the Nile, to the northeastern corner of Victoria Lake, where by a strait they gain access to another lake in quest of salt, possibly the Baringa of Dr. Krapf, which he, from information gained through the natives, called Salt Lake, most likely because there are salt islands on it, which reasoning I deduce from the fact that on my former expedition, when the Arabs first spoke to me of the Little Luta Nzigé, they described it as a salt-lake belonging to the great Nyanza; yet not belonging to it, when further pressed upon the subject. The Great Nyanza waters were purely fresh and sweet. They (the Arabs), like Dr. Krapf, merely narrated what they heard. As salt-islands were visited by the natives in search of that mineral, the surrounding waters naturally were considered salt by them, deprived as they were of its connecting links, which included the whole area of ground under consideration within the limits of the drainage system of the Nile. The Arabs, who, it is now very clear, had heard of everything in connexion with the science of physical geography, were enabled to connect what they had gleaned in detached fragments from it. Dr. Krapf further tells us of a river trending from the river Newey, by Mount Kenia, towards the Nile. If such is the case, it must be a feeder to the Baringa, whose waters pass off by the Asua river into the Nile, for the whole country immediately on the eastern side of the Victoria Nyanza is said by the Arabs, who have traversed it for ivory, to be covered with low rolling hills, intersected only by simple streaks and nullahs from this point in Muanza to the side streak, which is situated on the Equator, on the northern boundary of the Victoria Nyanza. Turning now again to Mashondé, and proceeding north along the boundary coast of Nyanza to the valley of Katonga, which, as situated on the quarter of the lake, is constantly in view, the land above the lake is beautiful, composed of low sandstone hills, streaked down by small streams-the effect of constant rains-grown all over by gigantic grass, except where the numerous villagers have supplanted it by cultivation, or on the deltas, where mighty trees, tall and straight as the blue gums of Australia, usurp the right of vegetation. The bed of the Nyanza has shrunk from its original dimensions, as we saw in the case of the Ujiji Lake; and the moorlands immediately surrounding are covered with a network of large rush-drains, with boggy bottoms, as many as one to every mile, even counting at one period a much fuller stream than at the present day, when the old bed was on the present surface of the water, and its breadth was double that which it now presents. The Mountains of the Moon are wearing down, and so is Africa. Crossing over the Equator altogether, the conformation of the land appeared much the same, but increased in beauty; the drainage system was found the opposite, clearly showing where in the north. slope of Africa one stream, the Mweranga, of moderate dimensions, said to arise in the Lake, flowed north, and joined the Nile in the kingdom of Unyroro, where its name is changed to Thafa. Far on, another stream,

the Luajerri, followed its example; and then still further on from the center of the Lake Nyanza's coast, issued the parent stream of the Nile, flowing over rocks of igneous character 12 feet high, which the natives, and also some Arabs, designate by the simple name of "stones." I have done myself the honor to christen it the Ripon Falls, after his Lordship, who was the President of the Royal Geographical Society when the expedition was set on foot. Now, proceeding down the Nile from the Ripon Falls, the river first bisected the sandstone hills which extend continuously into Usoga above the coast-line of the lake, and rushed along northward with mountain torrent beauty; and then, having passed these hills-of no great extent it turned through long flats more like a lake than a river, where, in Unyroro, it was increased by the contribution of the Kaffu and the Luajerri, and continued in this navigable form to the Karuma Falls in Chopi, where again, the land dropping suddenly to the westward, we saw the river rushing along with boisterous violence, but could not follow it, owing to the war which lay upon the track. It was, indeed, a pity, for by common report, not 60 miles from where we stood, the Little Luta Nzigé, which I had taken so much trouble in tracing down its course from the Lunæ Montes, with its salt islands in it, joined the Nile.

The main river was next met with in the Madi country, due north of the Karuma Falls, where it still bore the unmistakable character of the Nile,-long flats, long rapids. The southern half of the Madi was a flat, extending, we believe, to the junction of the Little Luta Nzigé; the northern, a rapid extending down to the navigable Nile, that is to say, the Nile which is navigable its entire length during the period of its flooding; and here it is that the Asua river of which we have heard, draining from the northeast corner of the Victoria Lake, joins; in a rainy season an important feeder, but when low, fordable. The first great affluent, which, indeed, is the only one worthy of remark on the left of the Nile, is the Bahr el Ghazal. The point of confluence presents the appearance of a diminutive lake at a sharp elbow of the Nile, and has hardly any visible stream of its own, whilst the great river winds round with a considerable velocity, carrying as I have said the palms with it. The second affluent in order of position, which, with all the others, is on the right of the Nile, is the Giraffe River, swirling with a considerable stream and graceful round into the parent Nile. Its magnitude and general appearance is like that of a first-class canal, inferior to the Kitangulé River, although not as much as to equal in volume one-third of the Nile at its point of junction. It is navigable to a great distance south; but where it comes from, nobody knows. It cannot be called a mountain river, as we found it full of rosets floating on its surface as in the Nile, evidently showing that both the trunk and the branch are subjected to the same alternations of sluggish flats and rapids. The third is the Southern Sobat River, which was full and navigable. In breadth it is greater than the Giraffe River, but less in velocity; so that we may infer their perennial contents are much the same. Unfortunately, the Northern Sobat was passed without our knowledge, which also being navigable, would make the Upper Sobat, that is to say, the Sobat above the Delta, of far greater magnitude than the Giraffe, unless, indeed, the three streams may be one river still further south, when in its combination the

comparison would have to be drawn with the Nile above it, which it would very nearly equal; for the Nile, with these additions, has scarcely doubled its importance, considered as it was seen from above entering the Bahr el Ghazal. The Blue River was long assumed to be the Nile only because its perennial powers were never tested. It appears to be a mountain-stream emanating in the country without the rainy zone, but subject to the influence of tropical rains and droughts, at one time full, and empty at another, or so shallow as to be fordable. The suspicion, therefore, that it was the Nile, must of itself appear absurd for its waters, during the dry seasons, would be absorbed long before they reached the sea. But apart from this feature of the volume of the Blue River, the Nile runs like a sluice in its wonted course; whilst the Blue River, conjoining with the Giraffe and Sobat, describes a graceful sweep. The Atbara, which is the last, is in all respects like the Blue Nile, only smaller. With one more remark I will conclude. In the height of the dry season in the White River, the Blue is freely navigated, owing to the great accessions of the Giraffe and Sobat Rivers, but below the Blue and Atbara Rivers to the sea, the sand banks obstruct further passage."

UNGER'S SCIENTIFIC RESULTS OF A TOUR IN GREECE AND THE IONIAN ISLANDS.-From the recent work of Prof. Fr. Unger, we derive the following epitome of his observations. His brief tour (March 25-June 10, 1860) was confined chiefly to Euboea and the Ionian Islands, and the results are contributions to their Botany and Geology. He gives a catalogue of 594 species of living plants collected by him, four of which being new are described in full, Biatora Ungeri, Neckera cephalonica, Neckera turgida, and Silene Ungeri, and with them a new variety of Evernia divaricata. Some fossil plants were found, especially at Kumi on the east coast of Euboea, from which place he gives descriptions and engravings of 56 species of a remarkably wide botanical range, belonging to no less than 41 genera and 29 natural orders. The fresh-water deposit which is seen here and in the northern Sporades appears also near the gulf of Smyrna, and even as far to the southeast as the Cilician Mt. Taurus. Specimens from this last locality were examined by our author and described ten years ago.

A geological and topographical chart of Corfu accompanies the work, showing the prevailing Cretaceous limestone (kreidekalk) with Tertiary basins in the centre and in the south. The highest elevation is in the north, St. Salvator, 2900 feet.

Several curious natural phenomena are discussed by Unger, as for instance, that at Argostoli on the west coast of Cephallenia, where the gulf waters flow inland through narrow channels disappearing under the rocks. The force of the water in one of them is sufficient to turn the wheel of a mill which has been in operation now thirty years. Where does the water go to? He supposes it to pass by subterranean channels to the salt and

brackish springs on the eastern side of the island, which are only one to one and a half feet above the sea level. The surface of the narrow gulf of Argostoli may be so much higher in consequence of the copious springs flowing into it at its head, as well as from other causes not yet observed. Similar salt springs have been observed in other parts of Greece, as the ancient Rheiti near Eleusis, and may perhaps hereafter be traced to marine sources.

To the question whether, so far as natural characteristics are concerned, the East is susceptible of a revival of its ancient prosperity, he gives an affirmative answer, having shown by compar ing ancient testimonies with his own observations that there has been no natural change there of any account.

F. P. B.

GUYOT'S PHYSICAL WALL-MAPS OF THE CONTINENTS.-A series of accurate Wall-Maps illustrative of the physical structure of the several continents, and of lesser portions of the earth's surface, has long been much desired by English and American teachers. The excellent maps which are published in Germany have never been widely introduced in this country, from the fact that the nomenclature, explanations and accompanying text are in the German language and are consequently obscure to many who would otherwise make use of the charts. At length, we have been furnished with an American series, which is not merely adapted in this respect to those who are only acquainted with the English language, but which is an original and important contribution to scientific cartography, and will be found in many particulars, as we believe, superior to other similar works.

The author of the maps is Professor Arnold Guyot, of Princeton, N. J., who has been for several years engaged in collecting his materials and in studying the best modes of presenting the generalizations of our knowledge of the surface of the earth. Two or three maps prepared by him were published in Boston several years ago, but although they were highly valued, their cost was too great to admit of their general introduction. Good as those were, the maps now published are much better fitted, in our opinion, for the illustration of geographical science. In their construction, Prof. Guyot has had the skillful aid of his nephew, Mr. Ernest Sandoz, whose ability as a draughtsman has been cultivated in the best European schools, and is all that could be desired in an undertaking of this kind. The result of their combined experience and study is satisfactory in a high degree. Each of these maps indicates by color the chief physical characteristics of the country it represents; the low lands having a green tint, the table lands brown, the mountain ranges black, and the highest peaks white. One or more cross sections are also delineated at the bottom of the map to exhibit in a still more

striking manner the predominant slopes and elevations. Besides this, the marine currents, the lines of equal temperature, the zones of vegetation and other physical phenomena are indicated. While these maps are not deficient in details, one of their chief merits consists in the fact that what is minute and special is made subordinate to what is general and extensive. By a skillful mode of drawing, those features of a country which constitute its chief characteristics are brought prominently before the eye, while the minor features are less boldly presented. At a glance it is easy to recognize what mountain chains, table lands, or water courses distinguish one continent or region from another; while a more careful scrutiny will bring out some of the details of the structure. The object seems never to have been lost sight of, that in such general maps as these, the essential, the predominant, the characteristic, should be given in clear, bold, lines; while that which is secondary and unimportant should either be omitted altogether or delineated in a subordinate style. Consequently the maps are not encumbered with minutia. They are eminently fitted for instruction in a class. Special topography can be acquired in hand-atlases, where an abundance of names is a merit rather than a superfluity; but in the lecture and the recitation such details are confusing to the eye and embarrassing both to the pupil and the teacher.

In addition to the exhibition of natural phenomena, the chief political divisions and the principal towns are also indicated on these maps, in a manner which does not obscure the physical features. The lettering is also well managed. Names are sufficiently frequent but are so printed as not to crowd the map, and indeed so as not to be read at the distance of a few feet. By devices of this kind, a great deal of detail is introduced without overrunning the map, and destroying the simplicity and clearness which are so important.

We have seen completed of this series only the maps of South America and the United States, but we understand that others are ready for publication. (New York: C. Scribner, 1863.)

PROF. WHITNEY ON THE HIGHEST MOUNTAINS OF THE UNITED STATES AND OF NORTH AMERICA.-Prof. J. D. Whitney, Superintendent of the California Geological Survey, discusses briefly in the California Proceedings, ii, 219, the question "which is the highest mountain in the United States and which in North America?" His conclusion is that Mt. Shasta, the height of which according to the barometrical measurements of the California Geological Survey, is 14,440 ft., probably overtops all other peaks within the limits of the United States. Mt. Hood, sometimes called the loftiest peak of the Cascade Range, is probably not so high as Mts. Shasta, Rainier, or Adams, and by no

AM. JOUR. SCI.-SECOND SERIES, VOL. XXXVII, No. 109.—JAN., 1864.