The Mont Cenis Tunnel. —The following particulars of the state of the works at Mont Cenis will be read with interest. We owe them to a recent report of M. Sommeiller, the engineer in charge. The length of the tunnel from Bardonnêche to Modena is 12,220 metres, and, at the end of 1804, 2,322 metres had been pierced on the Bardonnêche side, whilst the work had advanced 1,763 metres from the Modena end, making in all 4,085 metres—nearly a third of the whole distance. From the 1st of January to the 10th of June of the present year the progress of the work has been considerably augmented, upwards of 654 metres having been accomplished. The excavation is now, however, retarded by a mass of granite, which lessens the work of the machinery by one-third. The presence of this impediment was almost exactly predicted by MM. Elie de Beaumont and Sismonda, who stated, as a result of their survey, that granitic rocks would be met with at a distance of 1,500 or 2,000 metres from the mouth of the tunnel on the Italian side.
Lightning.—M. Boudin has recently laid before the Academy of Sciences a return of the deaths which have been caused by the action of lightning in France during the period 1835-63. During these thirty years 2,238 persons were struck dead. Among 880 victims during 1854-63, there were but 248 of the female sex; and in several instances the lightning, falling among groups of persons of both sexes, especially struck those of the male sex, and more or less spared the females. In a great number of cases flocks of more than 100 animals, [{277}] cattle, hogs, or sheep, have been killed, while the shepherds or herdsmen in their midst have remained uninjured. In 1853, of 34 persons killed in the fields, 15, or nearly half, were struck under trees; and of 107 killed between 1841-53, 21 had taken shelter under trees. Reckoning, then, at only 25 per cent, the proportion struck under trees, we find that of 6,714 struck in France nearly 1,700 might have escaped the accidents which occurred to them by avoiding trees during storms.
More about the Nile—Another source of the Nile has been discovered by the adventurous Mr. Baker, whose name has been frequently mentioned of late among geographers. But this so-called source is a lake only, the Luta Nzige, about two hundred and sixty miles long, and of proportionate breadth, which lies between the lake discovered by Captain Speke and the heretofore explored course of the Nile. The great river flows from one to the other, forming on the way the Karuma waterfall, one hundred and twenty feet in height, in which particular it represents the Niagara Fall between lakes Erie and Ontario. But it seems right to remark that the true source of the Nile has not yet been discovered, and that it must be looked for at the head of one of the streams which flow into the upper lake—the Victoria Nyanza of Speke. That the two lakes are reservoirs which keep the Nile always flowing, may be accepted as fact; but to describe them as sources is a misuse of terms. If Dr. Livingstone, in his new exploration, should get into the hill-country above the Victoria Nyanza, we might hope to hear that the real source, the fountain-head, of the Nile had been discovered. It is worthy of remark that these lakes of the Nile are laid down and described in old books on the geography of Africa. Ptolemy mentions them; and they are represented in some of the oldest Arabian and Portuguese maps. It is well known to scholars that the Emperor Nero sent two officers expressly to search for the head of the Nile. "I myself" writes Seneca, "have heard the two centurions narrate that after they had accomplished a long journey, being furnished with assistance by the king of Ethiopia, and being recommended by him to the neighboring kings, they penetrated into far distant regions, and came to immense lakes, the termination of which neither the inhabitants knew nor could any one hope to do so, because aquatic plants were so densely interwoven in the waters." This description holds good to the present day; and it is thought that certain rocks seen by the centurions mark the site of the Karuma Falls. Mr. Baker describes his voyage down the Luta Nzige as "extremely beautiful, the mountains frequently rising abruptly from the water, while numerous cataracts rush down their furrowed sides. . . . . . The water is deep, sweet, and transparent," and, except at the outlet of the river, the shores are free from reeds. "Mallegga, on the west coast of the lake, is a large and powerful country, governed by a king named Kajoro, who possesses boats sufficiently large to cross the lake." "About ten miles from the junction," he writes, "the channel contracted to about two hundred and fifty yards in width, with little perceptible stream, very deep, and banked as usual with high reeds, the country on either side undulating and wooded. At about twenty miles from Magungo, my voyage suddenly terminated; a stupendous waterfall, of about one hundred and twenty feet perpendicular height, stopped all further progress. Above the great fall, the river is suddenly confined between rocky hills, and it races through a gap, contracted from a grand stream of perhaps two hundred yards width to a channel not exceeding fifty yards. Through this gap it rushes with amazing rapidity, and plunges at one leap into a deep basin below."
The Burning Well at Broseley. —Mr. John Randall, F.G.S., writes to the "Geological Magazine" anent this extinct petroleum spring. The so-called burning well has ceased to exist for nearly a century. It was fed by a spring, and petroleum and naphtha also found their way from rents in the rock into the water of the well. Springs of petroleum on a much larger scale are met with in the neighborhood, and the yield of them was formerly much greater than at present. Many hogsheads from one of these were exported some years ago under the name of "Betton's British Oil," The rocks were tapped by driving a level through one of the sandstone rocks of the coal [{278}] measures; but these are now drained; and very little is found to flow from them.
The Origin of the Salt in the Dead Sea. —One of our most distinguished explorers of the Holy Land attributes the intensely saline character of the Dead Sea to the hill of Jebell Usdum. This is a huge ridge of salt, about a mile wide, and running N.E. and S.W. for a distance of three miles and a half, then due N. and S. for four miles further. It is situated near the southern extremity of the Dead Sea, and renders that portion of it much more salt than the northern portion. Further, Mr. Tristram thinks that it is the proximate cause of the saltness of the Dead Sea, the drainage to which has been dissolving away portions of salt, and carrying it to the Dead Sea, ever since the elevation of the ridge of Akabah separated the latter from the Red Sea, or since the desiccation of the ocean, which existed to the Eocene period, presuming (which seems most probable) that the fissures of the Ghor were of submarine origin, and that the valley itself was during the Tertiary period the northernmost of a series of African lakes, of which the Red Sea was the next.—Geological Magazine.
Iron Implements in Crannogues. —In a letter addressed to the London Reader, by Mr. George Henry Kinahan, some important points relative to the antiquity of iron, and the necessity for seeking for traces of this metal, have been dwelt upon. While investigating one of the largest crannogues or artificial islands in Loughrea, County Galway, Ireland, he found only stone implements, with the exception of a rude knife, which appeared to be of some sort of bronze. But he observed facts which would seem to indicate that iron implements had been in use among the inhabitants of the crannogues. These facts are as follows: 1st, All the stakes that were drawn had been pointed by a sharp cutting instrument, as were evidenced by the clean cuts. 2d, Pieces of deer's horn that were found had been divided by a very fine saw, as was proved by the absence of marks of graining on the surface of the sections. 3d, On some of the bones there were farrows, evidently made by sharpening fish-hooks or some pointed implement on them. 4th, In various places nests of peroxide of iron were observed, as if an iron instrument had once been there, but had been corroded away in course of time. Mr. Kinahan draws particular attention to the circumstances that "few metals corrode as fast as iron, and that, while stone and bronze would last for ages, iron would disappear, owing to corrosion, in a comparatively short space of time."
The Gibraltar Cave Fossils. —Mr. Busk in his paper on this subject says: The rock in which the caverns of Gibraltar were found is limestone, and extends for about three miles from north to south, at an elevation varying from 1,400 to 1,200 feet. It is geologically divided into three nearly equal portions by cleavages which separate the higher parts of the rock on the north and south from the central and lower part. At the southern face of the rock there is comparatively low ground, the Windmill Hill being about 400 feet above the level of the sea; but the strata there are inclined in an opposite direction to the great mass of what is termed the "Rock of Gibraltar." In the Windmill rock the caverns have been found, and in these latter a great quantity of bones was discovered. The bones, which were mingled with pottery, flint implements, and charcoal, appear to have been deposited at different periods, and were found at various depths, the lowest being fourteen feet below the floor of the cavern. Those in the lowest layer consisted of the bones of mammals, several of which were of extinct species. They were imbedded in ferruginous earth partially fossilized, and were covered with stalagmite—no human bones were with them. Above this layer were deposited the remains of about thirty human skeletons, with fragments of pottery, flint implements, particles of charcoal, and a bronze fishing-hook. Some of the pottery had been turned in a lathe, and bore evidence of classic art. In another cavern, discovered under the foundation of the military prison, the remains of two isolated skeletons were also found. Only one skull had been discovered there, and that had been sent to Mr. Busk, who remarked that the lower jaw transmitted with the cranium did not belong to it, showing that there must have been another skull [{279}] in the cavern, though no trace of it had been found. There was nothing in the form of the skull to distinguish it from the ordinary European type; but the bones of the leg were remarkably compressed; for which appearance it was difficult to account. Since Mr. Busk's attention had been drawn to this character, he had observed a similar compression in the leg-bones of other human skeletons which were known to be of great antiquity. Whether this conformation was to be regarded as a race-character, or was produced by special occupation or habit, Mr. Busk would not venture an opinion upon.—Social Science Review.
Sun's Photosphere. —From a strict examination of the sun-pictures obtained at Kew, near London, and from Mr. Carrington's maps, Mr. De la Rue and assistants hare arrived at the conclusion that the sun-spots are cavernous, and lie below the general level of the luminous surface, whilst, on the contrary, the faculae are elevated above the latter. The reason that the faculae appear brighter is, that on account of their height above the solar surface, they are less dimmed by passing through its atmosphere. They further conclude that the sun's luminous surface is of the nature of cloud, and that the spots are influenced by the planet Venus. They find that the faculae retain nearly the same appearance for days together, and consider them to be small particles of solid or liquid matter in suspension, and composed of the same cloudy matter as the luminous surface of the sun. They notice that in the majority of cases the faculae appear to the left of the spots, as if they had been abstracted from them, and, rising to a greater elevation where the velocity of rotation is greater, are consequently left behind. They remark that all the spots which are seen on the solar surface about the same time show a resemblance to each other; for instance, if one spot increases to the central line or past it, another will do the same; if one spot diminishes from its first appearance, another will do the same; if one spot breaks out on the right half; another will do the same. It appears from Mr. Carrington's and all the Kew pictures, that the influence of Venus is exerted in such a manner that as the spots approach the neighborhood of this planet by rotation they decrease; but as the solar surface passes away in the same manner, this influence causes it to break out into spots on the opposite side. The question is also proposed, whether the falling behind of the faculae may not be the physical reaction of the motion of the spots detected by Mr. Carrington, the current passing upward and carrying the luminous matter falling behind, whilst the current coming down from a colder region moves forward, carrying the spot with it, and accounting for its deficient luminosity.—Social Science Review.
The Arctic Expedition—The Open Polar Sea again—Last month we published an extract in which it was stated as the belief of the writer that there was an open Arctic sea. Here is another opinion which we find in the London Reader of a late date: "We have received from the Royal Swedish Academy of Sciences a map of Spitzbergen, with explanatory remarks in illustration (by N. Duner and A. E. Nordenskiöld). This beautiful map is the result of the two last expeditions undertaken to explore that group of islands. It is based upon astronomical observations, made at about eighty different places on the shores of Spitzbergen, with prism-circles by Pistor and Martins, mercury horizons and good chronometers by Frodsham and Kessels. The observations were calculated by Professors D. G. Lindhagen and Duner. The latitude and longitude of seventy-nine different points are given—the longitude of Sabine's Observatory, determined as 11° 40' 80", being taken as the starting point of the longitudes. The value of such a map is at once apparent. All the highest mountains were ascended during the expedition, and the height of twenty-eight peaks is given; the highest being Lindström's Mount of 8,800 English feet. The permanent snow-line commences at about 1,500 feet. The whole interior country forms an even ice plateau, here and there interrupted by rocks. There are many good harbors, and on this map the places are marked where the explorers anchored. Fish, fowl, and reindeer are to be met with in great numbers. We quote from the memoir as bearing upon one of the most interesting questions of the day. 'During the last years the idea has been vindicated that the Polar [{280}] basin is composed of an open sea, only here and there covered with drift ice. The learned geographer, Dr. Petermann, has even asserted that it would be as easy to sail from Amsterdam Island (70° 47') to the Pole, as from Tromsö to Amsterdam Island. This view is in itself so contrary to all experience that it scarcely merits refutation, but as different prominent English Arctic navigators seem inclined to adopt the same view, in spite of the experience gained by their own numerous Arctic expeditions, we will here give some of the most important reasons against this supposition. All who for a long period have navigated the northern seas, whalers and Spitzbergen hunters, have come to the conclusion that the Polar basin is so completely filled with ice that one cannot advance with vessels, and all the attempts that have been made to proceed toward the north have been quite without success. Passing by older voyagers, Torell and Nordenskiöld ascended, during the expedition in 1861, on the 23d of July, a high top on Northeast Land, Snötoppen (80° 23' L.), without being able, from that height, to see trace of open water to the north of the Seven Islands. A few days later, when the ice between Northeast Land and the Seven Islands was separated a little, they could push forward as far as to Parry's Island, though they, even from the highest tops on these islands (1,900 feet, 80° 40' L.), could see nothing but ice northward. From the top of White mountain, at the bottom of Wijde Jans Water (3,000 feet), we could, on the 22d of August, 1864, not see anything but ice between Giles Land and Spitzbergen. Some vessels that had the same year attempted to sail round Northeast Land were shut up by ice, and had to be abandoned by their crews. Before leaving the ships, an attempt was made to sail north, in order to return this way to Amsterdam Island, but they were soon met by impenetrable fields of ice. Notwithstanding a high prize has been offered for the reaching of high degrees of latitude, none of the whalers, who else sail boldly wherever the hope of gain allures them, have considered it possible to win this prize. We have had opportunities of speaking to most of the masters of vessels sailing to Spitzbergen. All experience hitherto acquired seems thus to prove that the Polar basin, when not covered with compact, unbroken ice, is filled with closely-packed, unnavigable drift-ice, in which, during certain very favorable years, some larger apertures may be formed, which apertures, however, do not extend very far to the north. Older narratives, by Dutch whalers, who are said to have reached 86° or 87° nay, even 89-1/2° must therefore be received with the greatest diffidence, if not looked upon as pure fictions, and the prospect of being able to advance with vessels from Spitzbergen to the Pole is, no doubt, extremely slight. It would be particularly unwise to choose the spring for such an attempt, and the passage east of Spitzbergen. At that time and by that passage it would be difficult, if not impossible, to reach even 78° of latitude. Whereas, on the west side, one can every year depend on reaching the 80th degree of latitude, and in favorable years it might be possible, in September or October, to sail even a couple of degrees higher.'"