five inches round. Scarcely any of them was so little as a musket bullet, but most of them far larger, and of that figure. Some indeed as large as hens' eggs, and of half a pound weight. Many sea-fowl and land-fowl were killed." 4. In Hertfordshire. By Mr. Robert Taylor. Phil. Trans. 1697. AT Hitchin, on Tuesday May 4, 1767, about nine in the morn. ing, it began to lighten and thunder extremely, with some great showers between. It continued till about two in the afternoon, when on a sudden a black cloud arose in the S. W. the wind being E. and blowing hard; then fell a sharp shower, with some hail-stones, which measured seven or eight inches about. But the extremity of the storm fell about Offley, where a young man was killed, and one of his eyes struck out of his head; his body was all over black with the bruises; another person nearer to Offley escaped with his life, but much bruised. In the house of Sir John Spencer, 7000 quarries of glass were broken, and great damage done to all the neighbouring houses thereabouts. The hail fell in such vast quantities, and so great, that it tore up the ground, split great oaks and other trees, in great numbers; it cut down great fields of rye, as with a scythe, and has destroyed several hundred acres of wheat, barley, &c. insomuch that they plough it up, and sow it with oats the tempest was such when it fell, that in four poles of land, from the hills near us, it carried away all the staple of the land, leaving nothing but the chalk. I was walking in my garden, which is very small, about thirty yards square, and before I could get out, it took me to my knees, and was through my house before I could get in, which was in the space of a minute, and went through all like a sea, carrying all wooden things like boats on the water, the greatest part of the town being under this misfortune. The size of the hail-stones is almost incredible; they have been measured from 1, to 13 and 14 inches about. Their figures various, some oval, others round, others pointed, some flat *. [Id. 1697. There is a subjoined account of a similar storm in the same county, in June 1697, during which the stones that fell, upon being measured, proved above nine inches in compass. [Editor. CHAP. XL. ON WINDS OR ATMOSPHERICAL CURRENTS. SECTION I. General Remarks on the Nature and Origin of Winds, Tradewinds, Monsoons, partial Winds, and Hurricanes. No o phænomenon in meteorology has more engaged the attention of men of observation than the winds, or those currents which so often disturb the tranquillity of the atmosphere. The subject is not only curious, but highly interesting; for upon their direction and force navigation in a great measure depends; the temperature of climates is greatly influenced by them; and they are absolutely necessary to preserve the salubrity of the atmosphere. To be ac quainted with the laws by which they are regulated, and to be able to calculate beforehand the consequences of these laws, has been in every age the eager wish of philosophers. But whether it has been owing to an improper method of studying this subject, or to its lying beyond the reach of the human faculties, philosophers have not made that progress in it which the sanguine imaginations of some individuals led them to expect. Many discoveries indeed have been made; and from the numbers and the genius of the philosophers at present engaged in this study, others equally important may be expected. But, notwithstanding this, many of the phænomena remain unexplained, and a rational and satisfactory theory seems still beyond our reach. I shall in this section give as complete a detail as possible of the natural history of the winds in the different parts of the world, and then consider how they may be explained. As the winds are much more regular between the tropics than in the temperate zones, it will be proper in the first place to begin with them. In those parts of the Atlantic and Pacific Oceans which lie nearest the equator, there is a regular wind during the whole year called the trade-wind. On the north side of the equator it blows from the north-east, varying frequently a point or two towards the north or east ; and on the south side of it, from the south-east, chang. ing sometimes in the same manner towards the south or east. The space included between the second and fifth degree of north lati. tude is the internal limit of these two winds. There the winds can neither be said to blow from the north nor the south; calms are frequent, and violent storms. This space varies a little in latitude as the sun approaches either of the tropics.-In the Atlantic Ocean the trade-winds extend farther north on the American than on the African coast; and as we advance westward, they become gra dually more easterly, and decrease in strength*. Their force diminishes likewise as we approach their utmost boundaries. It has been remarked also, that as the sun approaches the tropic of Cancer, the south-east winds become gradually more southerly, and the north-east winds more easterly: exactly the contrary takes place when the sun is approaching the tropic of Capricorn +. The trade-wind blows constantly in the Indian Ocean from the 10th degree of south latitude to near the 30th: but to the north. ward of this the winds change every six months, and blow directly opposite to their former course. These regular winds are called monsoons, from the Malay word moossin, which signifies "a season." When they shift their direction, variable winds and vio lent storms succeed, which last for a month and frequently longer; and during that time it is dangerous for vessels to continue at sea. The monsoons in the Indian Ocean may be reduced to two; one on the north and another on the south side of the equator; which extend from Africa to the longitude of New Holland and the east coast of China, and which suffer partial changes in particular places from the situation and inflection of the neighbouring coun. tries. 1. Between the 3d and 10th degrees of south latitude the southeast trade-wind continues from April to October; but during the rest of the year the wind blows from the north-west §. Between Sumatra and New Holland this monsoon blows from the south during our summer months, approaching gradually to the southeast as we advance towards the coast of New Holland; it changes Dr. Halley, Phil. Trans. Abr. vol. ii. p. 134. + Ibid. Dr. Halley, Phil. Trans. Abr. vol. ii. p. 136. about the end of September, and continues in the opposite direction till April. Between Africa and Madagascar its direction is influenced by the coast; for it blows from the north-east from October to April, and during the rest of the year from the south west t. 2. Over all the Indian Ocean, to the northward of the 3d de. gree of south latitude, the north-east trade-wind blows from October to April, and a south-west wind from April to October ‡. From Borneo, along the coast of Malacca and as far as China, this monsoon in summer blows nearly from the south, and in winter from the north by east §. Near the coast of Africa, between Mozambique and Cape Guardefan, the winds are irregular during the whole year, owing to the different monsoons which surround that particular place. Monsoons are likewise regular in the Red Sea; between April and October they blow from the north-west, and during the other months from the south-east, keeping constantly parallel to the coast of Arabia ||. Monsoons are not altogether confined to the Indian Ocean; on the coast of Brazil, between Cape St. Augustine and the island of St. Catherine, the wind blows between September and April from the east or north-east, and between April and September from the south-west 1. The bay of Panama is the only place on the west side of a great continent where the wind shifts regularly at different seasons: there it is easterly between September and March; but between March and September it blows chiefly from the south and south-west. Such in general is the direction of the winds in the torrid zone all over the Atlantic, Pacific and Indian Oceans; but they are subject to particular exceptions, which it is proper to enumerate. On the coast of Africa, from Cape Bayador to Cape Verde, the winds are generally north-west; from heuce to the island of St, Thomas near the equator they blow almost perpendicular to the shore, bending gradually as we advance southwards, first to the * Dr. Halley, Phil. Trans. Abr. vol. ii. p. 136. + Bruce's Travels, vol. i. p. 459. Dr. Halley, Phil. Trans. Abr. vol. ii. p. 156. Bruce's Travels, vol. i. ch. 4. ¶ Sir Walter Raleigh's Voyage. Forest's Voyage, p. 97. west and then to the south-west*. On the coast of New Spain likewise, from California to the bay of Panama, the winds blow almost constantly from the west or south-west, except during May, June, and July, when land-winds prevail, called by the Spaniards popogayos. On the coast of Chili and Peru +, from 20 or 30 de. grees south latitude to the equator, and on the parallel coast of Africa, the wind blows during the whole year from the south, va. rying according to the direction of the land towards which it in. clines, and extending much farther out to sea on the American than the African coast. The trade-winds are also interrupted sometimes by westerly winds in the Bay of Campeachy and the Bay of Hon. duras. As to the countries between the tropics, we are too little ac. quainted with them to be able to give a satisfactory history of their winds. In all maritime countries between the tropics of any extent, the wind blows during a certain number of hours every day from the sea, and during a certain number towards the sea from the land; these winds are called the sea and land breezes. The sea breeze generally sets in about ten in the forenoon, and blows till six in the evening; at seven the land-breeze begins, and continues till eight in the morning, when it dies away. During the summer the sea-breeze is very perceptible on all the coasts of the Mediterranean Sea §, and even sometimes as far north as Norway |. In the island of St. Lewis on the coast of Africa, in 16° north latitude, and 16° west longitude, the wind during the rainy season, which lasts from the middle of July to the middle of October, is generally between the south and east; during the rest of the year it is for the most part east or north-east in the morning; but as the sun rises, the wind approaches gradually to the north, till about noon it gets to the west of north, and is called a sea-breeze. Sometimes it shifts to the east as the sun descends, and continues there during the whole night. In February, March, April, May, * Dr. Halley, Phil. Trans. Abr. vol. 2, p. 136. + Sir Walter Raleigh's Voyage.-Dr. Garden, Phil. Trans. Abr. vol. ii. p. 132. Marden's Hist. of Sumatra, p. 17.-Buffon's Nat. Hist, vol. i. p. 385. Volney's Travels. Pontoppidan's Natural History of Norway. |