Abbildungen der Seite
PDF
EPUB

It appears from a paper published by M. Cotte in the Journal de Physique for October 1791, containing the mean quantity of rain falling at 147 places, situated between north lat. 11° and 60°, deduced from tables kept at these places, that the mean annual quantity of rain falling in all these places is 34:7 inches. Let us suppose then (which cannot be very far from truth) that the mean annual quantity of rain for the whole globe is 34 inches. The superficies of the globe consists of 170,981,012 square miles, or 686,401,498,471,475,200 square inches. The quantity of rain there. fore falling annually will amount to 23,337,650,812,030,156,800 cubic inches, or somewhat more than 91,751 cubic miles of water,

The dry land amount to 52,745,253 square miles; the quantity of rain falling on it annually therefore will amount to 30,960 cubic miles. The quantity of water running annually into the sea is 13,140 cubic miles; a quantity of water equal to which must be supplied by evaporation from the sea, otherwise the land would soon be completely drained of its moisture.

SECTION II.

Annual Fall of Rain, from Erxleben, Dalton, and others, with

subjoined Remarks.

25.0

[ocr errors]

Uusal. ................ Inches 16.7 Lyndon, Rutl. 21 y........... 24.3 West Bridgford, Notting. .... 17.0 Utrecht .......

24.7 Wittenberg.

........ 17.0 Haarlem ............... 24.7 St. Petersburg

17.2 Youngsbury, Hartf. 5 y. ... Lund .........

18.5 Kimbolton, Hunt, ......... 25.0 Diss, Norfolk ....

18.7 Norwich, 13 y. ....... 25.5 Upminster, Essex ..

19.5 Fyfield, Hampsh. 7 y. ... 25.9 Carlisle, 1 y. .......

20.2 Ferryby, Yorksh...... Paris ...............

20.2 Chichester ........... .. 26.8 Berlin ...

20.6 Ulm ..... Widdrington, North. 1 y....... 21.2 Algiers ...

.. 27.0 Rome 21.3 Barrowby, Yorksh. 6 y.........

.. 27.5 Edinburgh ........

22.0 Chatsworth, Derbysh. 15 y..... 27.8 Duolin

22.2 Hague .....

.............. 28.4 South Lambeth, 9 y.......... 22.7 Delft ...................... 28.6 London, 7 y. ................ 23.0 Harderwyk .................. 28.6 Near Oundle, North. 14 y....... 23.0 A place in Cornwall, 1 y....... 29.1 Lisle.........

24.0 Bristol, 3 y.................. 29.2

27.0

Bridgwater, Somers. .......... 29.3 Venice...

30.1 Abo ......

.... 29.3 Selbourne, Hampsh. .......... 37.2 Leyden .... ..... 30.2 Dover, 5 y. ..................

37.5 Madeira . 31.0 Lyons ..........

39.4 Minehead, Somers............. 31.3 Kirkmichael, Dumfr...... 40.8 Dalton's mean for all England, Ludgvan, Cornw. ......... 41.0

taking first a mean of the coun. Dordrecht ............ 41.0

ties ....... .......... 31.3 Townley, Lanc. 15 y........ 41.5 Mean of 16 places in Great Bri- Pisa ....

43.2 tain, Enc. Br............... 32.5 Lancaster, 10 y. ............. 43.0 Dalton's immediate mean of 32 Waith Sulton, Westm. 5 y, .... 46.0 places, mostly rainy ........ 35.2 Plymouth, 2 y. ....

46.5 Manchester, 9 y......

33.0 Charlestown................. 50.9 Middleburg ............. 33.0 Garsdale, Westm. 3 y, ....... 52.3 Zurich ..............

33.1 Fellfoot, Westm. 3 y.......... 55.7 Ereter .............. ... 33.2 Kendal, Westm. Il y. ....... 59.8 Liverpool, 18 y............ .. 34.4 Kendal, in 1782 .............. 83.5 Padua ..................... 34.5 Crawshaw booth, Lanc. 2 y..... 60.0 Cutte's mean of 147 places .... 34.7 Keswick, Cumb. 7 y. .......... 67.0 Sienna...................... 35.2 East Indies, sometimes ........1040

[ Young's Nat. Phil.

T

..

For rain and dew together Dalton makes the mean of England and Wales 36 inches, amounting in a year to 28 cubic miles of water.

From observations made in 1804 at Exeter, Chichester, Lon. don, Diss, Chatsworth, W. Bridgford, Ferriby, Lancaster, and Kendal, it appears that December was the wettest month in four of these places; June in two, May and November each in one, and April and December in one instance equally wetter than the rest.

Erxleben asserts, ii, 735, that the drops of rain at the equator are sometimes an inch in diameter.

Ulloa affirms that it never rains in Peru; but that for a part of the year the atmosphere is obscured by thick fogs, called garuas.

In some parts of Arabia it seldom rains more than two or three times in two or three years; but the dews are heavy and refresh the soil and supply the few plants, which grow in these regions, with moisture,

[Editor.'

SECTION III.

Fall of Butter-like Dew in different Parts of Ireland.

This curious phænomenon is noticed in two separate articles in vol. xix of the Philosophical Transactions. The first is an extract of a letter from Mr. Robert Vans of Kilkenny, dated Nov.15, 1695, as follows:

• We have had of late, in the county of Limerick and Tipperary, showers of a matter, like butter or grease. If this be rubbed on ones hand, it will melt, but laid by the fire, it dries and grows hard, having a very stinking smell. This last night some fell at this place, which I saw this morning. It is gathered into pots and other vessels, by some of the inhabitants of this place.”

The second article is still more minute, and proceeds from the well-known pen of the Bishop of Cloyne, bearing date April 1796.

6. Having very diligently inquired concerning a very odd pheno. menon, which was observed in many parts of Munster and Leins. ter, the best account I can collect of it is as follows: For a good part of last winter and spring, there fell in several places, a kind of thick dew, which the country people called butter, from the consistency and colour of it, being soft, clammy, and of a dark yellow ; it fell always in the night, and chiefly in moorish low grounds, on the top of the grass, and often on the thatch of cabins. It was seldom observed in the same places twice: it commonly lay on the earth for near a fortnight, without changing its colour ; but then dried and turned black. Cattle fed in the fields where it lay indifferently, as in other fields. It fell in lumps, often as large as the end of one's finger, very thin and scatteringly; it had a strong ill scent, somewhat like the smell of church-yards or graves; and indeed we had during most of that season very stinking fogs, some sediment of which might probably occasion this stinking dew, though I will by no means pretend to offer that as a reason of it: I cannot find that it was kept long, or that it bred any worms or insects ; yet the superstitious country people, who had scald or sore heads, rubbed them with this substance, and said it healed them."

[Phil. Tran, 1696.

We have already had occasion to observe that substances of va. rious kinds are frequently carried into the atmosphere by their own levity or other force. Fat or butter is nothing more than a mixture of hydrogen and carbon in certain relative proportions to each other. Both these substances are often extricated from the surface of the low moorish grounds here referred to ; and from their affinity to each other, very generally ascend in combination, forming what the chemists call hydro.carbonat, or carburetted hydrogen gas: and hence, in the instance before us, the combina. tion of these two substances, was in all probability such as to produce the unctuous material here described*. [EDITOR.

SECTION IV.

Dense Fog on the Island of Sumatra.

By William Marsden, Esq. In the year 1775 the S. E. or dry monsoon, set in about the middle of June, and continued with very little intermission till the month of March in the following year. So long and severe a drought had not been experienced there in the memory of the oldest man. The verdure of the ground was burnt up, the trees were stripped of their leaves, the springs of water failed, and the earth every where gaped in fissures. For some time a copious dew falling in the night supplied the deficiency of rain ; but this did not last long: yet a thick fog, which rendered the neighbouring hills invisible for months together, and nearly obscured the sun, never ceased to hang over the land, and add a gloom to the pros. pect already but too melancholy. The Europeans on the coast soffered extremely in sickness; about a fourth part of the whole number being carried off by fevers and other bilious distempers, the depression of spirits which they laboured under, not a little contributing to hasten the fatal effects. The natives also died in great numbers.

* The substance called Honey-dew does not regularly belong to this division of our work. It is usually an excrementitious secretion of various insects that adhere to the lower sarface of the leaves of plants; and we shall notice it accordingly in the subsequent divisions of the Gallery of Nature and Art, which will be found to comprise the curiosities of Zoology. The dew of plants is in like manner an aqueous secretion from the secernent vessels of plants.

EDITOR.

In the month of November that year, the dry season having then exceeded its usual period, and the S.S. winds continuing with unremitting violence, the sea was observed to be covered, to the distance of a mile, and in some places a league from shore, with fish floating on the surface. Great quantities of them were at the same time driven on the beach or left there by the tide, some quite alive, others dying, but the greatest part quite dead. The fish thus found were not of one but various species, both large and small, flat and round, the cat.fish and mullet being generally the most prevalent. The numbers were prodigious, and overspread the shore to the extent of some degrees ; of this I had ocular proof or certain information, and probably they extended a considerable way farther than I had opportunity of making inquiry. Their first appearance was sudden; but though the numbers diminished, they continued to be thrown up, in some parts of the coast, for at least a month, furnishing the inhabitants with food, which, though attended with no immediate ill consequence, probably contributed to the unhealthiness so severely felt. No alteration in the weather had been remarked for many days previous to their appearance. The thermometer stood as usual at the time of year at about 859.

Various were the conjectures formed as to the cause of this extraordinary phenomenon, and almost as various and contradictory were the consequences deduced by the natives from an omen so portentous; some inferring the continuance, and others, with equal plausibility, a relief from the drought. With respect to the cause, I must confess myself much at a loss to account for it satisfactorily. If I might hazard a conjecture, and it is not offered as any thing more, I would suppose, that the sea requires the mix. ture of a due proportion of fresh water to temper its saline quality, and enable certain species of fish to subsist in it. Of this salu. brious correction it was deprived for an unusual space of time, not only by the want of rain, but by the ceasing of many rivers to flow into it, whose sources were dried up. I rode across the mduths of several perfectly dry, which I had often before passed in boats. The fish no longer experiencing this refreshment, ne. cessary as it would seem to their existence, sickened and perished as in a corrupted element.

[Phil. Trans. 1781.

« ZurückWeiter »