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These elements represent the normals upon which they are founded very closely, considering that observations of comets in 1815 did not pretend to the degree of precision which is now sought to be attained, and, moreover, were subject in the reductions to errors in the places of the comparison stars.

But Bessel's labours did not stop here. With a special interest in the comet of 1815, not, it may be presumed, alone due to its exceptional character, but in no small degree to the circumstance of its having been detected by his most intimate and revered friend, Olbers, Bessel undertook, and in the year of its appearance accomplished, the laborious task of computing the perturbations of the planets Jupiter, Saturn, and Uranus upon the motion of the comet during the present revolution, and so determining the epoch of the next perihelion passage. The principal details of this work are comprised in the memoir to which we have already referred. The masses of Jupiter and Uranus were Laplace's, while the mass of Saturn was taken from Bouvard's tables. The whole period is divided into three sections, the first extending from August 4, 1815, to July 30, 1833; the second from the latter date, with new. values of the semi-axis and excentricity to July 21, 1869, and the second from July 21, 1869, to the next perihelion passage. The action of each of the three planets tends to accelerate the comet's return, that of Jupiter by upwards of two years; the final result indicating an acceleration of 824 51 days, with reference to the period belonging to Bessel's definitive ellipse for 1815; it was thus found that the duration of the actual revolution would extend to 262224 days, and consequently the next perihelion passage is fixed to February 94, 1887. This conclusion will be affected not only by the imperfect values of the planetary masses which were available when Bessel undertook the investigation, but in a greater degree by the uncertainty which still remained as to the precise length of the revolution at the last appearance; this Bessel found to extend to ± 0.27657 of a year, or 101 days.

With such an amount of probable error attaching. to Bessel's result it must soon be a matter for the consideration of the astronomer, whether a nearer approximation may not be yet attained. We have much more accurate values of the masses of Jupiter, Saturn, and Uranus than Bessel possessed, and are able to take into account the influence of Neptune, though this is not likely to be very material. Fortunately, in several series of observations, the observed differences of right ascension and declination between the comet and the comparison stars are preserved to us, and thus we can reduce the observations anew, with much improved positions of many of the stars and with modern elements of reduction. The series of observations thus available include the long one of Olbers (Berliner astronomisches Jahrbuch, 1818), and those of Greenwich, Paris, and Dorpat. It is a work which, together with the recalculation of the perturbations to the next perihelion passage, may perhaps be made the subject of a prize by one or other of our scientific academies; on the last return of Halley's comet, the first approximation to the epoch of arrival at perihelion was due to action of this kind on the part of the Academy of Turin, and though a much higher degree of interest attached to the reappearance of that famous body, we do not despair to see Olbers' comet deemed worthy of a new and more refined calculation.

If these cometary bodies wandering into the confines of the solar system from the stellar spaces are fixed therein by the action of one or other of the planets, it will have been owing to a very close approach to the planet Mars that Olbers' comet presented itself in 1815, moving in an ellipse of moderate dimensions. The nearest approach of the two orbits in that year was o'07 in 86°4 heliocentric longitude, but [this distance must have varied in successive revolutions through the perturbations of the other planets, and at some past time there may have been an intersection of the orbits and a close encounter of the two

bodies.

METEOROLOGICAL NOTES

BEFORE the commencement of the summer rains this year Mr. Eliot, the officiating meteorological reporter to the Government of India was called upon for a report on the prospects of the season. His reply, to which we have already referred in the "Notes," consisted of a short résumé of the most important characteristics of the southwest monsoons of recent years, from which the following conclusions were deduced:-"1. The persistent excessive pressure over Northern India at the present time (June, 1878), tends to diminish the baric gradient between Southern Asia and the Mid-Indian Ocean, and if this is not compensated by increased pressure over the sea area to the South of India, the monsoon current will be below its average strength. 2. There appear to be no stronglymarked abnormal variations of pressure over Northern India. It is therefore probable that the rainfall will be much more equally distributed than last year. 3. Comparing the present year with 1865, it is probable that the heavy rainfall during the cold weather, and more especially in May, will slightly retard the advent of the monsoon in Upper India. 4. The probable effect of the low pressure along the Bombay coast cannot be determined except by comparison with last year. It appears to promise fairly abundant rain over that portion of the country." These conclusions have now been subjected to the test of experience and are found to have been verified in almost every particular. The southerly current from the Indian Ocean has been decidedly below its normal strength; the rains set in from a fortnight to a month after the usual time; every district in the country has received a moderate supply of rain, though the average rainfall for the whole country has been less than usual, and over the Bombay Presidency, from Belgarum to Kurrachee, the rainfall has been in excess of the average for previous years. only peculiarity of the monsoon of 1878, that was not predicted, was the frequent recurrence of heavy falls of rain over a few small and well-defined areas; but this would seem to be the character of the rainfall of every year in which the monsoon current is of less than the usual strength. The percentage of verifications reached by Mr. Eliot has thus been as great as that attained by the American observers, and the predictions in his 'case were made months, not days or hours, in advance. The same meteorologist has recently made a discovery which promises to be of the greatest possible value in connection with the system of storm-warnings to the ports round the Bay of Bengal. It is that a cyclonic vortex, when generated in the middle of the Bay, always travels towards that part of the coast where the wind velocity for the time being is least in comparison with the average velocity for the same place and time of year. This law has been verified by almost all the cyclonic disturbances that have occurred in the Bay since a chain of meteorological observatories was established round it, and it lends a great deal of support to the theory that a cyclonic vortex is developed through the accumulation, concentration, and condensation of aqueous vapour over a region of comparative calm. All that appears now wanted to

The

render cyclone prognostications for the Bay of Bengal almost absolutely certain is a submarine cable to the Andaman and Nicobar Islands, by which the meteorological stations on these islands, near the place of origin of all the great cyclones of the Bay, would be brought into telegraphic communication with the rest of the empire.

IN his "Tenth Contribution to Meteorology," which appears in the American Journal of Science and Arts for the present month, Prof. Loomis gives the results of an examination he has made as to the course of seventyseven storms after leaving the eastern coast of the United States, these storms having occurred from March, 1874, to November, 1875. Of these seventy-seven storms he was able to follow thirty-six of them entirely across the Atlantic Ocean, eight of them, however, becoming merged in other storms before reaching Europe. The annual average of storms which are found to cross the Atlantic from the United States to Europe is eighteen, and nearly all of these storms pursued a course north of east, passing in their eastward course considerably to the north of Scotland; indeed, in only four of the storms did the centre pass as far south as the north of England. Prof. Loomis concludes that, when a storm with a centre depression at least below 29.5 inches leaves the coast of the United States, the probability that it will pass over any part of England is only one in nine; that it will occasion a gale anywhere near the English coast, one in six; and that it will give rise to a fresh breeze, one in two. A characteristic feature of these storms is the slow rate of their onward progress in crossing the ocean, as compared with their rate over the United States-a feature of the utmost possible importance in attempting to predict the time of their descent on the shores of Europe of those American storms which cross the Atlantic. About half of the whole number of the storms originated in the neighbourhood of the Rocky Mountains, five in or near Texas, and four were distinctly traced to the Pacific coast. Of six West India cyclones which occurred in the same time only two could be traced across the Atlantic, and even one of these became blended with another storm. The rest of the paper is taken up with a discussion of the fluctuations of the barometer on Mount Washington, 6,285 feet, and Pike's Peak, 13,960 feet, as compared with what takes place on the level ground at the base of these mountains. As regards Mount Washington, the valuable result is arrived at that the diurnal maxima and minima of the barometer occur more than three hours later at the summit than at the base, showing an average retardation of one hour for each 900 feet of elevation. In the case of Pike's Peak, the rate of retardation is one hour for an elevation of 1,380 feet. It is evident from these figures that the law of the rate of retardation is yet to be sought, one of the most important factors, in all probability, being the absence or presence of high plateaux and their extent near the high station, to which must be added the latitude of the place. Observations of the wind at these high levels show, just as at places near sea-level, a circulation about a low centre, the movement of the wind being approximately at right angles to the direction of the low centre; and further, that at the height of Mount Washington, the low centre of storms sometimes lags behind the low centre at the surface of the earth as much as 200 miles. This last result is so vital in the theory of storms as to demand a much more extended examination, the most special care being taken that the retardation of the time of occurrence of the diurnal barometric minima be allowed for in the discussion.

IT is with extreme satisfaction we learn that at a recent meeting of the Council of the Scientific Association of France, M. Mascart, Director of the Meteorological Department, submitted a proposal from the Departmental Commission of Vaucluse, for the establishment of an

observatory on the top of Ventoux, situated to the northeast of Carpentras, and rising above all the surrounding summits to a height of 6,300 feet above the sea. This observatory in the south of France, along with the observatories of Puy de Dôme in the north, and of Pic du Midi in the south-west, may be regarded as furnishing France with an enviable system of elevated observatories for meteorological observations such as no other country possesses, thus putting French physicists in possession of the essential data whence the more difficult meteorological problems may be attacked, and the systems of weatherwarnings for navigation and agriculture more rapidly developed and improved. It is estimated that 150,000 francs will be required to establish the station, of which sum there are already subscribed by M. R. Bischoffsheim 10,000 francs, by the Commune of Bédoin, situated at the foot of Mt. Ventoux, 10,000 francs, the Council of the Scientific Association 500; and as the Meteorological Commission of Vaucluse has opened a subscription-list, the General Council of the Department has promised to aid in forming the roadway up the mountain, and a subsidy is looked for from the Minister of Public Instruction, the establishment of this important observatory will doubtless soon become an accomplished fact.

GEOGRAPHICAL NOTES

WITH reference to the reports that Prof Nordenskjöld's vessel had got shut in by the ice near East Cape, in Behring Strait, the Committee for Promoting Russian Trade and Industry have resolved to apply to the Governor-General of Eastern Siberia, requesting him to assist in instituting a search for Prof. Nordenskjöld, and in obtaining more certain information as to the situation of the expedition. Mr. W. H. Dall, the well-known U.S. Alaska explorer, has written a letter to an acquaintance in Stockholm, mentioning the previously-reported statement of whalers, from which it is supposed that the Vega, has been stopped by ice east of Cape East. Should this be the case, Mr. Dall entertains no fears for the fate of the expedition. If these suppositions be correct, he says, "the breaking up of the ice next July will leave open water for the Vega to proceed to Behring Strait. Vessels pass to westward of East Cape every year. There is a creek there. (The letter here gives a sketch map describing a bay, with a small island in the middle of it, and an anchorage inside.) A river with fresh water runs into the bay, and on the coast is a native village. This is not marked in the ordinary maps and charts, and it is just here that the vessel, according to the repots of the natives, must be lying. She can safely winter there. There is a large village, inhabited by Tchuktchees, who would be able to supply fresh meat. This place is situate not more than 200 English miles from the white men's trading station at Plover Bay. If the Vega is lying there, the success of the operation is practically achieved, because, as I said, the bay is open every year, and does not get closed by ice until October. Vessels sail there, and carry on trade every summer."

THE last number of the Isvestia of the Russian Geographical Society contains an interesting paper by M. Grigorieff, on the temperature and density of water in the Arctic Ocean, along the coast of Russian Lapland, and in the White Sea, being the result of observations carefully made on board the schooner Samoyede, by means of good instruments. As to the Arctic Ocean, M. Grigorieff confirms the existence of a warm branch of the Gulf Stream which flows along the coast as far as Gavrilovskiye Islands, and thence turns due east to the Kanin Peninsula and Kolgueff Island, and further, to the Moller Bay on Novaya Zemlya. Beneath this warm current there is a cold one flowing in an opposite direction at some depth. When it meets with a rising bottom, and especially with the deep bank of less than 100

fathoms under 71° N. lat., this denser and cold current is compelled to change its direction, and makes its way between the Gulf Stream and the shore; hence the low temperatures and great density of water at the Lapland coast, in the space between Svyatoy Nos and the Seven Islands. The density of the eastern (North Cape) branch of the Gulf Stream (1025 to 1026, figures which correspond to a percentage of salt of from 328 to 3'41), seems to be smaller than that of the Spitzbergen branch, where Nordenskjöld has found a percentage of salt as high as 3 625. As to the White Sea, M. Grigorieff denies the entrance of a branch of the Gulf Stream into that sea, as was supposed some years ago by Prof. Middendorff; the Gulf Stream does not penetrate further than the Gulf of Mezen, and the warm temperatures observed by Middendorff are due to purely local causes. On the contrary, a cold polar current enters the White Sea along the Tersky coast, whilst the current which flows out of the sea into the ocean, follows the Winter and Kanin Coasts. The water of the White Sea on the whole has a very low temperature, especially in the deeper parts; on depths more than 100 fathoms the temperature is always below 32° Fahr., and this, because of the great loss of heat during the long winter. Altogether, the observations having been made and computed very carefully, and published in extenso in the Isvestia, are a real acquisition to science.

Two new expeditions to Central Asia are planned in Russia for the next spring. The first, by Col. Prjvalsky, to Hlassa in Thibet, and thence to Afghanistan; and the other, by M. Blumenfeld, a German savant who has studied in Russia, for botanical and geological explora. tions; M. Blumenfeld will follow nearly the same route as that proposed by M. Prjvalsky.

UNDER the title of "D'Orenbourg à Samarkand" Madame de Ujfalvy has commenced in the Tour du Monde an illustrated account of her travels in Ferghanah and Western Siberia. Leroux, of Paris, has just brought out the first volume of M. de Ujfalvy's account of the results obtained during his mission. These results are mainly ethnological, and contain many observations and careful and detailed measurements of a large number of individuals representing the various races of that part of Central Asia visited by the traveller and his wife.

DURING the year 1878 the following accounts of Russian exploration were published in Russia: that of Col. Prjvalsky to Lob-Nor, now translated into English; of M. Wojeikoff in India and Japan; rather literary than scientific is that of M. Minayeff on his journey to India, which contains very interesting observations on Buddhism; of M. Ogorodnikoff to Persia, giving among other data an account of the trade-routes to Persia and Afghanistan; and of M. Skalkofsky to Eastern Asia and California.

As Sir H. Rawlinson has announced his intention of delivering an address at the next meeting of the Geographical Society, on the road to Merv from the Caspian, it will not be without interest to note some particulars respecting the earlier part of the route, as far as the Tekké fort of Kizil Arvad, from an account lately furnished to the Moscow Gazette by a writer who appears to have been attached to General Llamakin's staff. The party were obliged to strike eastwards from the Chikishliar littoral by a road which has never yet been described, but which is the most practicable route to the Attrek, the bank of that river, from its mouth at Hassan-Kuli Bay almost to Balt Adji, being bordered by inapproachable morasses. The ground traversed was at first covered with shells, but soon presented the appearance of a salt marsh petrified by the sun; then, after a stretch of sand, firmer soil was met with. No water was found until the wells of Karadji-Batyr were reached. About twelve versts

from the wells the party arrived at the gates, as it were, of an enormous wall, which bore a greater resemblance to an artificial structure than to a natural conformation of the soil. Three versts further on the valley of the Attrek appeared in sight, with the river itself winding between high and verdant banks. Here is Bayat-Adji, a name which is also applied to the whole of the surrounding country. From this spot the party proceeded up the Attrek to Chat or Chad, following an excellent road. About ten versts before reaching Chat the road turned to the left, leaving the Attrek at a point where there are large auls, or settlements of the Atabai tribe. At length Chat was reached, and it is described as the most repulsive place along the whole Attrek, although from a strategical point of view the most important, because it is here that the River Sumbar (which Capt. Napier calls the Sunt) flows into the Attrek, and the delta might be made an impregnable position. Fifty versts above Chat two enormous rocks rise out of the Attrek, forming a sharp delimitation of the geological structure of the country. This place is called Su-Sium; after this point the road is impassable for camels, and 10 versts further on is difficult even for horses; 100 versts beyond Chat the course of the Attrek can only be followed on foot, and it would take three months to make the road practicable. In consequence of the difficulties mentioned, the party was obliged to abandon the course of the Attrek at SuAfter making the Sium, and to strike a new road. necessary surveys they turned to the left at a place called Alun-Yak, and proceeded over the high Sugundag chain. The ascent and descent of the Sugundag extends over a distance of 16 versts, the descent terminating at the small River Chandyr, which falls into the Sumbar. Twenty-five versts from Chat the party crossed the Sumbar, and marching between that river and the Chandyr, reached an elevated mountain called Bek-Tépé, belonging to the spurs of the Kurindag. Leaving the Sumbar they proceeded through the waterless defiles of the Ters Akon, and through the Morgo defile (belonging to the Kaplandag range), and reached the ruins of HadjanKala, near the Tekké fort of Kizil Arvad. The road through the defiles presents many difficulties, and only two horses can proceed along it abreast, but it is thought that a good road could be made without much trouble or expense.

THE Society for Promoting Christian Knowledge publishes a very excellent small wall-map of Africa, by Stanford, containing all the most recent discoveries and useful both for teaching and general purposes.

ON January 25 the Geographical Society of Paris will hold a public reception in the large hall of the Sorbonne, in honour of MM. de Brazza and Ballay, the two French Ogowé explorers. The great medal for 1879 will be delivered on this occasion by Admiral La Roncière le Nourry, the president of the Society.

No. 78 of the Zeitschrift of the Berlin Geographical Society contains a careful geographical and statistical study on the Brazilian province of Rio Grande do Sul, by M. Bescharn. Botanical. students will be interested in Dr. Klunzinger's elaborate paper on "The Vegetation of the Arabian Desert near Koseir." This number contains a carefully arranged, most complete, and valuable bibliography of geographical literature and cartography for the year from November, 1877, to November, 1878.

No. 3 of Globus of this year contains a fine illustration of the wonderful reclining statuary figure of Chac-Mool, unearthed in Yucatan some time ago by M. le Plongeon. The same number contains the sixth contribution of Herr Zehme to a résumé of recent exploration in Arabia.

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we may undertake to pass from the Pliocene Country to the ocean we shall be compelled to cross some of the loftiest barriers of the Continent. It is hemmed in by range after range of high mountains. The winds laden with moisture are wrung dry long before they reach the plateaux in the heart of the province. The prevailing wind throughout the year is from the westward, and must cross the Sierra Nevada. Sweeping across the great basin it blows over many ranges, and at last strikes the Wasatch and the chain of high Plateaux which form the

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with their myriads of wonderful shapes and their astounding architecture-are due, as we shall presently find, in great part to the aridity. The aridity is due to the great barriers which surround it, and above all to that great barrier of high plateaux which lies upon its western verge. Here, then, we may look for another key which may unlock another door within the vestibule. The search will not be fruitless.

last four years a field of special study by myself, and has The district of the high plateaux has been during the

been investigated as thoroughly as circumstances and my
very limited qualifications would admit. Its original
attraction consisted in the enormous displays of volcanic
energy there in former times, to which I cannot here
venture to allude any further. The structure of the district
is also otherwise very interesting, and has been worked out
with much care and patience, and in great minute-
ness of detail. It will be possible at present to
give nothing more than a categorical statement of
certain results. To master the evidence would re-
quire the handling of a large amount of detail, and
unwarrantably protract discussion.

The structure of these plateaux is identical with what Prof. Powell has described as Kaibab structure, being in fact a northward continuation of the same belt which he has described and delineated in his well-known section of the Grand Cañon which cuts across this series of displacements at a right. angle. The faults which have blocked out the plateaux and intervening valleys are of prodigious length, and the amounts of dislocation are very great

greater in the high plateaux than in the Kaibabs. The age of these displacements is an important landmark in the history of the country, and that age can be fixed with confidence as late Pliocene, and continuing into the Quarternary, and probably down to the présent time.

With this fact in our possession as a datum we come now to the history of the cañons. The Grand Cañon first makes its appearance in the epoch of the faults. It suddenly bursts into view as a less than half-formed thing, with walls ranging from 2,000 to 2,700 feet high, late in Pliocene times. But it presents itself under somewhat unexpected circumstances, for it had been in the condition in which we first find it for a considerable period. The work of vertical erosion had long been suspended, the channels had ceased to grow deeper, and the energies of the river had for an unknown period been employed in another kind of occupation to which rivers have been frequently known to betake themselves under certain common conditions. It was widening its cañon and making a flood plain in which to meander. This any river will inevitably do when it has sunk its channel to the limiting depth which local circumstances prescribe for it. When that limit is reached it will attack its own banks whether they be walls of rock or nothing but gravel and loess, and will thereafter meander or squirm from side to side. There are numerous places along the Upper Colorado and its tributaries where this is abundantly exemplified. From local. causes the fall of the river has for a space been diminished, the flow has been sluggish, sediment. has been deposited, the river has ceased to erode its bottom, it has attacked its walls, and the cañon has been widened..

If now the reader will look at the section of the Grand Cañon (Fig. 3) he will perceive that it is a cañon within a cañon. The walls are in two leaps with an intermediate terrace. The upper or outer cañon is usually from three to six miles wide, and the inner cañon meanders within the upper, sometimes close to one upper wall, sometimes to the other, but usually with a middle terrace on both sides. The inner and the outer cañon represent two periods, the outer one of course being formed first-formed no doubt originally as a narrow gorge which was widened while the river was unable to cut vertically. The middle terrace is the final flood plane of the old cañon. And now the faults come to our assistance in determining the two periods. The outer cañón is older than the faults; the inner one is coeval with them. The reasoning by which we determine

this is of the simplest order. If we were to see a fault. cutting a particular stratum we should know that the stratum was older than the fault. By parity of reasoning we know that the outer cañon is older than the faults. because they cut its trough and dislocate its floor transversely. If the faults were older the river would have

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FIG 4.-Pa-ru-nu-Weep Cañon, Virgin River, a tributary of the Colorado. planed an even grade across them regardless of the dips. of the strata just as it is doing to-day 3,000 feet below. As it is-if the side gorges would permit us to travel along the middle terrace-we should be compelled every time we crossed a fault to clamber up or down its face.

Thus, then, as we draw near the close of the Pliocene

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