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but still a great rain for that day. The are of short continuance, though frequent, classing of the rain might have been ex in which case less value is attached to these tended further, into very great rains, or so ; of course, and are multiplied by 4 or 5, inbut no advantage could be derived from such stead of 6, according to circumstances; the an arrangement, as will appear from the first instance of this kind is in the winter rules obtained from this article, which will be and year 1815-16, and also in 1816-17, found most wonderfully consistent and regu “ In estimating the quantity of frost in a lar. It is to be observed of showers, that season, the days or nights on which this when these are frequent, they inake up a phenomenon appeared, are termed a day of moderate rain, and even on rare occasions a frost, and the number of these in a season great rain, but very generally only a short are simply the number of the frost. rain; the time and the effect in these cases accurate comparative sum might have been are considered.
obtained, by a clasification similar to the “ The method of finding the sum of rain rain, viz. hard frost, moderate frost, and in a season is this : Taking an extreme slight frost, which might gratify the curious; case for an example, winter 1804-5, it had but there was labour enough without this 5 great rains, 12 moderate, and 25 short addition.
the great rains are each supposed Of the other phenomena of weather, víz. equal to 6 short, and the moderate to 3 short thunder, lightning, aurora boreales, &c. it rains; and these being added to the actual has been only necessary to note them in the number of short rains, the whole sum is 91 order of appearance, giving the sums of each short rains ; but as this number has been at the end of the season or year, as will be considered an inconvenient one, particularly found in the tables in the history of the wcaas it would require in general three figures, ther; only remarking here, that however it is divided by 4 on all occasions, which frequent the thunder or lightning is on any reduces the product to two figures, at least day, it counts but as one day with thunder, by the seasons, which was the first mode of &c. treatment of the subject adopted, the System by years having been found long after ;
By observing the number of days of therefore, 91 being divided by 4, the quo
east and west wind for 14 years, Mr tient is 224; but as no fractions are admit- Mackenzie found, that the average ted in the sum of rain for a season, the sum number of days of east wind was 135, total is called 23 for this winter. Any other and the average number of days of mode would have served as well, if continu. west wind 216, a ratio which, for reaed throughout, but this appeared the sim
sons afterwards to be mentioned, he pleşt, and the result has fully warranted its continuance, and for the reason
considers as approaching to that of 140
ated, as to the rules obtained in consequence of this ar
to 210, or 2 to 3. If the east wind, on rangement, it giving an exceeding correct any given year, shall amount to more result; moreover, it was absolutely neces than the average of 135 days, there is sary to find a round sum, as the representa- then an excess of so many days of east tive of the variety of the rain which falls in wind, but if it amounts to less than 135, a season, which has the advantage of sim- there is then & deficiency of so many plifying the subject, so as to be easily under days of east wind.
The same is stood and recollected.
done with the west wind; and the “ In estimating the sum of rain-snow, hail, and sleet, are always included.
excesses or deficiencies of both winds
As an enumeration is made of the days' snow
are put down for each year. As in a season, it is explained thus : Any the phenomena of the weather can day upon which snow falls, is termed a have no relation to our civil year, Mr snowy day, though probably a greater pro- Mackenzie begins the weather year, as portion of the fall may have been in rain : he calls it, upon the 1st of November, this distinction has been made, merely to because it is at or near this period that shew the prevalence of snow upon any sea there is the most material change of son : thus it will be seen that the second
weather during the whole year, and winter observed, that of 1803-4, though a mild winter, yet there was an extraordinary that this is the only day which gives
the quantity of snow as well as of rain.
averages leading to the system, or “ The sum of the force of the wind is rather, it comes out strongest on this found much in the same manner as the rain : day, gradually becoming weaker before. Thus, there are gales, and high winds, and and after, till it disappears altogether on windy days; but the high winds are classed the 26th October and the 5th November. under gales, and each supposed equal to 6 Having in this manner found the excesa windy days, and the sum thus found are added to the actual number of windy days winds for 14 years, he began to com
ses and deficiencies of the east and west in a season ; the whole then is divided by 4, which is a common divisor, and the quotient pare them together, and was surprised represents the sum of the force of the wind to find, that they followed one another for the year. It happens, however, on rare in a regular progression, the excesses occasions, that the gales and high winds and deficiencies of both winds arranga
ing themselves in groups,
The na In the preceding scale, the number túre of this progression will be under- of the series of excesses and deficienstood froin the annexed table, consist- cies of both winds is exactly equal, ing of three columns. The first column viz. 24 groups of each ; but if we contains the Years of Observation, the reckon them individually, we shall first of which commenced in 1802-3, find, that the excesses east are 24, and or on the 1st November 1802. The the excesses west 30; and that the defisecond column contains the Excesses ciencies east are 30, while the deficienand Deficiencies of the west wind, and cies west are only 24. Hence the east the third the Excesses and Deficiencies wind is one-fourth less in excess, and of the east wind. Upon comparing one-fourth more in deficiency than the these E's and D's, it appears, that in the west ; that is, it blows one-half less east wind column the Excesses are frequently than the west, or the two grouped in the following manner, EEE, winds are to one another as 2 to 3, a EE, E, and the Deficiencies, which are result which harmonizes in a very sina interposed between them in the fol- gular manner with the ratio of 135 to lowing manner, viz. D, DD, DDD, 216, deduced by Mr Mackenzie from DDDD. In the west wind column the 14 years' observation. progression is E, EEEE, EEE, EE, Although it is absolutely necessary, and DD, D, DDD. Now it is a very from the nature of the cycle, that the remarkable fact, that by following out excesses and deficiencies of the east these progressions the series returns and west wind shall return every 54 into itself in 54 years, forming a per- years ; yet it by no means follows, that
the weather in any one cycle shall in FORM OF THE SYSTEM.
every respect resemble the weather in any other cycle. The time of excess
and deficiency of both winds may be Year. West. East. 1. E.
constantly varying, and may be per28. E. D
forming another periodical change of 2. D.
29. E. E. 3.
greater or less extent.
“ It must therefore become desirable,” 5. E.
says Mr Mackenzie, “ to ascertain how far 32. D. D.
one revolution of the system of the weather E. D. 33.
D. corresponds with another in every particu. 7. E. E. 34.
lar; and if journals, conducted upon a suf8. D. E.
D. ficiently circumstantial plan, can be found, 9.
something of a solution of this point may be 10. E. D.
accomplished.” 37. D. E. 11. E. D.
We have thus endeavoured to give 38. D. D. 12. D. E.
our readers some notion of the general 39. D. 13. D. D.
system delivered by Mr Mackenzie. 14. D. D.
This, however, forms a very small por41.
E. D. 15. E. D.
tion of his work, which contains also E.
Particular Rules of the Weather, de43. E. 17.
duced from observation; the History 44. 18.
of the Weather from 1802; the Laws 45. D. D. 19. E. E.
of the Wind; and the Distribution of 46. E. D. 20. D.
the annual series of the Wind upon 47. E. D. the seasons. As it is in the power of 21. E. E.
48. E. E. E. E.
every person to examine, by their own 49.
experience, the accuracy of the rules 23. E. D.
50. E. D. for the weather, we shall lay before 24. E. D.
E. D. our readers some of the most import25. D. E. 52. D. D.
ant. D. D. 53. D. D.
1. An extraordinary wet winter is 27. D. D. 54.
D. E. followed by average rain in the sumBy this systematic arrangement, the 55th
mer succeeding. year is the same with the first, and the 56th
2. An extraordinary dry winter is the same with the second, and so on.
followed by an average summer.
3. After a winter with a rate of rain It is singular, that this period of 54 moderately under average, and anoyears should be thrice the Chaldaic period ther immediately after at average, the of eclipses of 18 years 11 days.
succeeding is moderately above average.
OF THE DISASTER
4. When there are two seasons to very curious part of it relative to the gether, either summer or winter, distribution of the wind upon the seasomething considerably under aver sons, without entering into tedious age, the succeeding iš average ; and details ; and we must therefore conthe season following, which is the tent ourselves with recommending the fourth, respectively, is very wet; and careful perusal of his book to all those the next, or the fifth, is very dry, but who are interested in the very imnot always an extreme dry; for an portant subject of which it treats. Diextreme dry is only to be expected ligent and careful observation is the when the extreme wet is suddenly only test by which the system can brought about.
be tried. Upon this foundation the 5. Two average summers together author rests: it; and he is therefore are followed by a very dry one in the entitled to have it candidly and carenext year, and this by a very wet one, fully examined. which is succeeded by a dry one.
6. When two wet winters, or two wet summers, come together, neither are ever in extreme.
THE VAL DE 7. When a winter and a summer
BAGNE, IN THE BAS VALAIS, AND are wet in succession, the succeeding winter is dry; and when a summer
IT IN JUNE 1818. * and a winter are wet in succ sion,
(We are indebted for the following inte. the next summer is a dry one.
resting article to our friend Professor Pictet 8. When a summer and a winter of Geneva, who has had the goodness to are average in succession, the next send it to us, previous to its appearance in summer is either wet or dry.
his own excellent Journal, the Bibliotheque 9. No three seasons together in suc
Universelle. cession, or respectively, are ever wet
The Val de Bagne is a transverse vale average, or dry. 10. No three seasons whatever, Valais : it cuts, almost at right angles,
ley in the high southern chain of the taken in succession, or respectively, many other smaller chains, forming have ever more rain above average, part of the great mass of mountains collectively, than is to be found in one
which separates Switzerland from Piedseason of extreme wet, and vice versa.
mont, 11. After every course of wet, there ley of Bagne intersects these different
At every point where the valis a course of dry, however short or
chains, it is rendered extremely narlong either may be, and vice versa.
row. In many of these gorges, the 12. A mild winter is followed by a mild summer.
Dranse, which occupies the bottom, is 13. A wet summer is always follow- the pick, leaving only a very narrow
confined in a rocky channel cut with ed by a frosty winter.
bed, from whence it passes into 14. Every frosty winter is in gene
more extensive basons formed in the ral followed by a cold summer. 15. An excess of west wind in win- before the late melancholy event, pre
lower part of the valley, and which, ter is followed by much thunder in
sented level plains, covered with the the following summer, provided the excess west be preceded or followed by
* This interesting account contains a deexcess east in the summer, and if both
tailed report of what was verbally related, happen, the thunder is still more con
on the 29th of last month, to the Helvetic siderable.
Society of Natural Science, at Lausanne, 16. A deficiency of west wind in by Mr Escher de la Linth, who was witness winter greatly diminishes the thunder to the disasters he describes. He illustrated in summer.
his relation by a model of the valley, formed 17. An excess of east wind in summer of clay jointly by him and Mr Venetz, an is followed by thunder in the winter,
engineer of the Valais, who was of eminent and there is 'never thunder in winter service in very critical circumstances. This but after an excess of east wind in model, which spoke to the eye while the
reporter addressed the judgment and the
feelings, rendered quite luminous all those It would be impossible to give any details which the imagination can present to explanation of the other portions of us but imperfectly without such assistance. Mr Mackenzie's work, particularly the
richest verdure, and studded with For some years back, however, the beautiful groups of houses and barns, glacier of Gétro has advanced so far shaded by lofty trees.
upon the ridge of the rocks which The southern chain of the valley, form the upper side of this extensive setting out from the separation of the channel, that enormous masses of ice Val de Bagne from the valley of Entre are constantly falling into it from the mont, which leads to the Hospice of glacier above, and are swept over by the St Bernard, rises very soon to the ele- waters of the cascade with a tremenvation of perpetual snow, and forms dous crash, Part of them are caught the most northerly point of the icy upon the steep ledges of the rocks of peaks of Mount Combin. The northern the gorge; the remainder falls down chain does not rise so abruptly, and into the bottom of the valley, where only reaches the line of perpetual these fragments accumulate more or snow at Mount Pleureur, situated less, according to the quantity of ice six miles distant from the entrance which the glacier furnishes, and the of the valley. Thus far this chain season accelerates or retards the melte separates the Val de Bagne from the ing of them. great valley of the Rhone ; but, at It is now five years since the accuthat point where it rises to the line of mulation of these blocks of ice, falling perpetual congelation, it takes a south- from the edge of the glacier of Gétro erly direction, and then separates the into the bed of the Dranse, began to Val de Bagne from the valley of form a new glacier in the shape of a Hyères, which, like the former, is half cone, whose summit is in the a lateral branch of the great valley ravine, about a hundred feet above the of the Rhone. Mount Pleureur de- bed of the river, and whose base so scends very rapidly into the valley of completely fills up this part (always a Bagne, and there forms with Mount narrow one) of the Val de Bagne, that Mauvoisin, which rises opposite to it, the side of this icy cone, inclined to a pretty long gorge, in which the about forty-five degrees, leans, to the Pranse is confined in a channel of extent of two hundred feet, against from twenty to forty feet in breadth, the almost perpendicular base of Mount and whose sides shoot up vertically to Mauvoisin, which is opposite to the the height of about a hundred feet, so glacier of Gétro, in the chain on your that the bridge of Mauvoisin, which right hand as you ascend the valley of connects the two sides of the valley, Bagne. rests iipon perpendicular rocks eighty This new glacier, which thus absofeet above the bed of the river.
lutely closes up the bottom of the By the side of Mount Pleureur, valley, is certainly not exclusively towards the bottom of the valley, rises composed of fragments of ice fallen Mount Gétro, whose steep sides, formed from the top of the glacier of Gétro : into steps by the strata of the rocks avalanches of snow seem to have had composing the mountain, and having a part in the formation of it; and but little inclination, are in some parts after this collection of ice and snow covered with pasturage, where there became once thick enough to resist are many chalets in very lofty situa the transient heat of the preceding tions. A very narrow and pretty deep summer, it is clear that the snow of channel separates Mount Ĝétró from the following winter, added to the new Mount Pleureur. The glacier of Gétro avalanches of ice and snow collected is situated at the top of it, and forms in this fatal ravine, was more than the most advanced point, towards the sufficient to enlarge the new glacier, north, of that great uninterrupted range which, by means of rain water and of gluciers which, from the Great St melted snow filtering into it and Bernard, as far as the Simplon, crown freezing anew, composed at last a hothe vast chain of the Alps which di- mogeneous mass of ice, of so enormous vides Switzerland from Piedmont. a bulk, that the period of its destruc
At all seasons, the water of the gla- tion cannot be calculated. cier of Gétro falls in cascades into the In the meanwhile, the waters of the ravine, which descends with a very Dranse, which are supplied by the rapid fall into the Dranse, at the upper glacier of Tzermotane and some others end of that gorge in the valley where at the head of the valley, and which the bridge of Mauvoisin is situated. already form a pretty large torrent, still
found an outlet under the glacier, the finished on the 13th of June. During base of which was doubtless thawed these thirty-four days the lake rose by the heat of the earth, and that of sixty-two feet ; but during eight days, the water passing under it. Already, in the increase of its waters having, on the course of last year, the river had account of the falling of the temperabeen obstructed by the glacier for a ture of the atmosphere, only raised the considerable time; but it suddenly level four feet, the upper entrance of opened for itself a passage, which did the gallery was still many feet above considerable damage in the lower part the level of the lake ; and the intrepid of the valley, even as far as Martigny. Mr Venetz had thus time to sink the
It was in the month of April last, floor of that opening several feet, in however, that the waters of the Dranse order to accelerate the efflux of the were observed to be dammed up in lake, and thereby diminish the mass the bottom of the Valley of Bagne, of water which was indefinitely accuforming a lake of half a league in mulating. length. The danger of a sudden ef During the dangerous working of flux of the lake, the surface of which this gallery, extending to 608 feet in was rising and extending every day, length, through the thickness of the was too imminent not to lead to the glacier, masses of ice, of many thouadoption of every possible means to sand cubic feet, were detached from prevent such a disaster. It was re the base of the glacier on the side of solved to cut a subterraneous gallery the lake. The fragments, after fallthrough this enormous cone of ice, ing into it with a crash, ascended to sixty feet lower than the line of con the surface, forming small floating ice tact of the new glacier with the islands. These accidents shewed the side of Mount Mauvoisin, a level at risk which the workmen in the galwhich the new lake, which was al- lery ran, at every instant, of being ways increasing, would necessarily crushed to pieces and buried under pour itself into the lower part of the the glacier. valley, if the opposing glacier could On the evening of the 13th of June, resist the enormous pressure of the at the moment when the water began mass of water accumulated above it. - to issue from the gallery, now happily The point at which the draining gal- finished without any serious accident, lery was carried through the glacier, the lake was from ten to twelve thouwas fixed at the elevation which the sand feet long; its medium breadth, lake was expected to reach at the pe- at the surface, might be seven hunriod of its completion. It was dred feet, and at the bottom one hunpected that, in consequence of this ar- dred feet. Thus its absolute metificial outlet, the water, in passing dium breadth was four hundred feet, through it, would gradually furrow and its absolute medium depth two the bottom, and, of course, lower it, hundred. The lake, therefore, conwhile the surface of the lake, by tained, at the period of its greatest that means, would subside in the same height, at least eight hundred millions proportion, thus daily diminishing the of cubic feet. risk of the rupture of the glacier, and From the evening of the 13th of the sudden efflux of the water which June, to the 14th at eleven o'clock in it retained. This operation, which was the forenoon, the lake still continued admirably calculated to obviate the to rise a little, notwithstanding the impending danger, was executed un outlet by the gallery. After this peder the direction of Mr Venetz, an riod the bottom of the gallery began engineer of the Valais, with unshaken to wear down, owing to the melting perseverance and courage, in spite of of the ice over which the water flowthe difficulties which every day pre- ed; and by five o'clock of the evening sented themselves, and the danger of of the same day the lake had descendworking in a place where blocks of ice ed a foot. On the 15th of June, at were constantly falling from the upper 'six o'clock in the morning, the floor glacier, and in a mass which was lia- of the gallery was so much lowered, ble at every instant to be undermined that the height of the lake was dimiby the lake, or rent in pieces and car nished ten feet, and twenty-four hours ried off by the enormous pressure of after was less by thirty, feet. On the the water. This perilous undertaking 16th of June, at six o'clock in the was begun on the 10th of May, and evening, being the moment at which Vol. IV.