Зображення сторінки
PDF
ePub

drawn; but progression, Heaven's great law of consummation, cannot fail, nor the agencies sink into slumber, by which all things are impelled toward the goal. Even monotonous seasons are expressive. They address both our reason and our faith : they are but prognostics of coming scenes of greater interest ; as the silence which was in heaven “ for the space of half-an-hour," omened the extraordinary events of the last seal, and the fulfilment of “the mystery of God.”

THE BRITANNIA, ICEBOUND, IN BOSTON HARBOUR. IT appears there had been [during the winter of 1844] a frost of unusual intensity, such as had not been known for more than half a century, which caused the sea to be frozen over in the harbour of Boston, although the water is as salt there as in mid-ocean. Moreover, the tide runs there at the rate of four or five iniles an hour, rising twelve feet, and causing the whole body of the ice to be uplifted and let down again to that amount twice every twenty-four hours. Notwithstanding this movement, the surface remained even and unbroken, except along the shore, where it cracked. Had the continuance of this frost been anticipated, it would have been easy to keep open a passage ; but on the 1st of February, when the Britannia was appointed to sail, it was found that the ice was seven feet thick in the wharf, and two feet for a distance of seven miles out; so that waggons and carts were conveying cotton, and other freights, from the shore to the edge of the ice, where ships were taking in their cargoes. No sooner was it understood that the mail was imprisoned, than the public spirit of the whole city was roused, and a large sum of money instantly subscribed for cutting a canal, seven miles long, and one hundred feet wide, through the ice. They began the operation by making two straight furrows, seven inches deep, with an ice-plough drawn by horses, and then sawed the ice into square sheets, each a hundred feet in diameter. When these were detached, they were made to slide, by means of iron hooks and ropes fixed to them, under the great body of the ice, one edge being first depressed, and the ropes being pulled by a team of horses, and occasionally by a body of fifty men. On the 3d of February, only two days after her time, the steamer sailed out, breaking through a newly-formed sheet of ice two inches thick; her bows being fortified with iron to protect her copper sheeting. She burst through the ice at the rate of seven miles an hour, without much dainage to her paddles; but, before she was in clear water, all her guard of iron had been torn off. An eye-witness of the scene told me that tents had been pitched on the ice, then covered by a slight fall of snow, and a concourse of people followed and cheered for the first mile, some on sleighs, others in sailing-boats, fitted up with long blades of iron, like skates, by means of which they are urged rapidly along by their sails, not only before the wind, but even with a side-wind, tacking and beating to windward, as if they were in the water.

The Britannia, released from her bonds, reached Liverpool in fifteen days, so that no alarm had been occasioned by the delay; and, when the British Post-Office department offered to defray the expense of the ice-channel, the citizens of Boston declined to be reimbursed. - Sir Charles Lyell.

BRITISH ASSOCIATION FOR THE ADVANCEMENT OF

SCIENCE.*

ON ATLANTIC WAVES, THEIR MAGNITUDE, VELOCITY, AND PHENOMENA. DR. SCORESBY had had, for many years, opportunities of observing the magnitude and velocity of waves; and more recently, in returning by the steamer “ Hibernia" from Boston, in the spring of 1848. For such observations steam-ships present peculiar advantages. In scudding before the wind, the paddle-boxes on either side prevent the rolling of the vessel to any great extent; and the ship, when in the trough of the sea, is almost perfectly steady for several seconds together. There are also different platforms from which observations may be made—from the deck, the saloon or cuddydeck, and the paddle-boxes. In the case of the “Hibernia,” on the occasion referred to, he had ascertained that the height of the eye on the saloondeck, above the line of flotation, was about twenty-three feet three inches, and on the paddle-boxes thirty feet three inches. On the 5th of March, 1848, lat. 51.28, lon. 30, it blew a hard gale at sunset, with the barometer at 29.50. Next morning, at ten o'clock, it stood at 28.30, when the scene was terribly magnificent. Looking from the saloon-deck, almost every wave was above the eye, and consequently more than twenty-four feet above the trough, or twelve above the mean level of the sea. He then ventured on to the paddle-box; and when the ship was completely within the trough of the sea, which even its great length could not span, at least half the waves rose above the paddle-boxes, and many, as determined from the angle of elevation, considerably higher. The height of the average highest waves must have been forty-three feet above the level at which the ship floated. The appearance the ocean then presented was one of the grandest he had ever beheld. During the swell which continued after the storm, the waves were still of great height, but reduced, on the average, to about twenty-four feet. Whilst the mean elevation of the highest waves, from the hollow of the trough, was forty-three feet, occasional wave-crests were raised still higher. The general average of the time occupied by the waves in overtaking the ship was 164 seconds. The length of the vessel was 220 feet, and the waves were six seconds in passing from stern to stem, thus giving (after variations for ship's progress and obliquity of course) the probable distance of the waves from crest to crest, of 559 feet. In determining the mean velocity of the wave, reference must of course always be had to the velocity of the ship at the time. During the time which elapsed between successive waves overtaking the ship, the vessel, as was ascertained by her rate of sailing at the time, had advanced so much as to make the actual distance accomplished by the waves in 16 seconds, 790.5 feet, so that their velocity was about 32.67 English miles per hour; or, assuming the largest possible error, certainly thirty miles per hour.

MR. Scott RUSSELL observed that Dr. Scoresby's observations have thrown much light on this subject, and he bore testimony to the accuracy of Dr. Scoresby's mode of measuring the height, which is perhaps the most difficult point, and also the velocity of the waves. From smaller waves, only sixteen inches broad, Mr. S. Russell has predicted, in tables published some time ago in the Transactions of the Association, that waves

* These notices are, in the main, abridged from the long-established journal to which we have already acknowledged ourselves indebted.--Edits.

559 feet long will be found to have a velocity of from thirty to thirty-one miles per hour. And it must be gratifying to the lovers of science to learn that, until Dr. Scoresby came into the room this morning, he had never heard or seen anything of these tables. In such observations as those which had just been read, the three main points to be noted were, 1. The greatest height of the wave ; 2. The distance from the top of one wave to the top of another; and, 3. The period of oscillation of the wave.

LATE RESEARCHES IN GREECE.

The country of Agamemnon (said PROFESSOR RANGABE, of Athens) is found to be covered with a great number of edifices belonging to the time of the Anactes. Captain Soitoux, one of the most indefatigable members of the French Commission, saw in the wild ravines of Acarnania more than thirty foundations of towns, of Cyclopean construction. In Arcadia—the dwelling-place of the Pelasgians, who pretended to have seen the creation of the moon, and who at least preceded the Hellenic race-polygonical walls are discovered every day; and in a valley unknown to travellers, between the Lake Stymphalus and the Mount Trachys of Orchomenos, I had myself the happiness, two years ago, of discovering, at the very spot where Pausanias (viii. 23) places it, the town of Halea, long sought for, and not as yet perceived by any of my predecessors. This ruin presents one of the most imposing examples of Pelasgic architecture, and at least two-thirds of it are in a state of rare preservation.

I was present at the excavations made at Tyrinth by the illustrious German antiquarian, Thiersch ; and I witnessed the highly interesting result which he obtained. On the western side of the hill of the Cyclops, he discovered a range of bases of columns; and this fact, combined with one or two others, tends to modify the ideas held until now on Pelasgic architecture, and to prove that the principle of the column-of a primitive form, undoubtedly, but containing the germ of the diverse forms developed later by the Dorians and Ionians—was, if not an indispensable part, at least an ornament frequently employed in the buildings of Homeric times.

*

The Parthenon, when delivered of the barbaric ruins which insulted its grandeur, had still secrets to disclose ; and it is well known that attentive observations have taught the astonished architects of modern times, that of all those lines whose magnificent harmony is the source of the inimitable beauty of this edifice, there is not one which is a straight line; that with a depth of science which would put to fault the calculations of the profoundest mathematician, the architect, imitating nature, which avoids a straight line in her organic productions, had composed a system of curves beyond the skill of modern art to combine or reproduce.

The Erechtheum, that enigma of architecture, can also be better understood since it has been raised from its ruins; and in my opinion it is now evident that this temple was double, in spite of its having four names, and that the singular distribution of the house consecrated to Erechtheus which it replaced had been adopted in its construction. The new notions obtained on this temple have been most ably discussed in the Annals of the Academy of Munich, by the learned philologian of Germany, M. Thiersch, who is now preparing a second work on the same subject.

VARIETY OF CLIMATE IN FRANCE.

M. Le DR. CA. Martins exhibited a map of France, divided into six climates, marked both by different ineans and different extremes of temperature, by differences of summer and winter temperature, direction of winds, &c. 1. The Vosgian ; 2. The Sequanian ; 3. Armorican; 4. Girondin; 5. Rhodanian; 6. Mediterranean. 1. The Vosgian occupied the north-east of France, and was the coldest of all. The mean temperature of winter is scarcely more than 32 degrees of Fahrenheit. In Strasburg, the number of days of frost is seventy, while, at Paris, they are only fifty-six. The maxiinum number of days of rain is in summer; a circumstance which distinguishes it from all the other regions of France, where the greatest number of rainy days is in the autumn. The prevailing winds are the north-east and south-west. Storms are more frequent in this climate than in the west of France. The summers are also warmer than in the west ; and hence, while the vine does not thrive near Paris, it thrives on the banks of the Moselle. 2. The Sequanian may be termed a sea-climate. In Alsace, the difference between the mean temperatures of summer and winter is 18 degrees of the centigrade thermometer; but at Paris, in the Sequanian climate, it is only 14 degrees. The quantity of rain is also less than in the east of France, and storms are more rare. 3. The Armorican is an insular climate, with only 12 degrees between the mean temperatures of summer and winter, with a fall of from 700 to 800 of rain yearly. The quantity of rain is greatest in autumn. 4. Girondin climate is more continental than the Armorican, and the influence of the sea is less marked. The number of rainy days is fewer, and the quantity of rain less. The summers also are warmer, and the winters milder, so as to give it more of the character of a temperate region, with a climate highly favour. able to the production of grains and fruits. 5. The south-east or Rhodanian climate may be termed a warm continental climate. The summers are warmer, and the winters less severe, than in the district of the Vosges; but the difference between the mean temperatures of these seasons is about the same, or 18 degrees cent. The annual quantity of rain is the greatest in France, giving rise to inundations of the Rhone, which are often very destructive, unless they be carefully guarded against. The prevailing wind is not the south-west as in the rest of France, but the north and south, and the great falls of rain are accompanied by a south-east wind. Storms and earthquakes also are more frequent in this than in the other climates. 6. Mediterranean, or Provençal climate, is one of a peculiar kind, and is more like that of Genoa and the north of Italy than of France. The mean annual temperature is higher than in any other part of France, and is nearly 15 degrees. Although the annual quantity of rain is 500 millimetres, it all falls in a few days, chiefly in the autumn. The summer is remarkably dry. Storms are not common, but very violent, This climate would be altogether the finest in France, were it not for a north-west wind called the Mistral, which blows with extreme violence down the basin of the Rhone, and is very injurious both to the crops and fruits, and even to the health of the inhabitants. It seems to have been scarcely known until the cutting down of the forests in the south, which formerly protected this region from its fury. M. Martins stated, that they had begun the publication of a work, containing the results of the meteorological observations made in France from year to

year, two volumes of which he presented to the British Association, for which the thanks of the Section were returned.

GEOGRAPHICAL DISTRIBUTION OF HEALTH AND DISEASE,

Beautifully illustrated by maps and diagrams, the atmospheric effects of climate on man were comprehensively traced in MR. Keith Johnston's able paper. The chief points in the communication may be stated thus :Endemic fever, including remittent and intermittent fever, prevails in North America, the West-India Islands, the west coast of Africa, Syria, South Italy, the Ionian Islands, and in general in the low marshy districts of warm countries. Yellow fever is endemic in North America and the West-India Islands, between latitude 5 degrees and 40 degrees north ; its northern limit in Europe being the latitude of Gibraltar. Diseases of the digestive organs are most prevalent in India, West and East Africa, the Cape of Good Hope, England, Guiana, &c. Disease of the liver greatly predominates in the East Indies ; while consumption is most conspicuous in Great Britain, Newfoundland, Canada, and Jamaica. Dropsy is most prevalent in West Africa, Great Britain, and Guiana. Among the different countries the most striking contrasts are sometimes exhibited : thus the west of Africa is to Europeans most fatal, while the south-east is the most healthy country in the globe. The effect of the means adopted for checking disease in the three great countries of England, France, and Germany, during the past century, is such, that while formerly one out of every thirty of the population died each year, now the average is one in fortyfive,-reducing by one-half the number of deaths in these countries. In the year 1700, one out of every 25 of the population died in England. In 1801, the proportion was one in 35; in 1811, one in 38; and in 1848, one in 45; so that the chances of life have in England nearly doubled within this period. In the middle of last century, the rate for Paris was one in 25 ; now it is one in 32.

THE LUNAR SURFACE.

Some time ago, Mr. Nasmyth's attention had been directed to the remarkable appearances on the surface of the moon, in connexion with the light they seemed to throw on the study of geology ; and he had procured some considerably powerful telescopes in order to observe them more particularly. He exhibited to the Section a variety of drawings from nature, which had been taken by himself from what he had observed. The largest was a map, on a great scale, of the entire lunar surface, on which was strikingly depicted the peculiar nature of that surface, crowded with craterlike cups, in some places so close as to overlie each other, and, as it were, elbow each other out of the way. The other views were various portions of the surface which had been selected for more minute study. These representations had all been drawn from observations made in the most favourable circumstances, and with great care ; and the result was, that the conclusion was even stronger than in the case of the earth, that it was once wholly in a molten condition. The central cones observed in three fourths of the lunar mountains show plainly that the formation observed is volcanic. These cones, in the case of terrestrial volcanoes, are the result of the expiring action of the volcano, after the eruptive energy has ceased to be able to project the molten mass over the sides of the crater. And the same thing has taken place in the moon. Many of its volcanoes are sixty

« НазадПродовжити »