causes may, and probably will, be discovered; the circumstances in which they take place, and the effects which they produce, may become familiar to us; and whenever this is the case, the winds of any place might, in some measure, be reduced to calculation.*.

(373.) In regard to the direction of the wind, I may mention only, in reference to this country, that the predominant winds are from the westerly direction, and of these the SW. prevails, and it prevails most in the months of July, August, and September. The NE. wind blows always in the spring and early summer months, as in April, May, and June; but they are most severely felt on the east coast. This table shews the comparative prevalence of the westerly and easterly winds in Great Britain, the former comprehending all those from N. to S. by the W., and the latter those from N. to S. by the E.

(374.) It may prove useful to enumerate a few places at which registers of the wind are kept, to shew you the results in different parts of the kingdom. 1. In London, by a mean of 10 years of the register kept by the Royal Society, these results were obtained :

It appears from the particulars of this register, that the SW. winds blow, at an average, more frequently than any other wind during every month of the year, but that it blows longest in July and August; that the NE. winds blow most constantly in January, March, April, May, and June, and most seldom in February, July, September, and December; and

• See Polehampton's Gallery of Nature and Art, vol. iv. p. 185–205; in which an interesting collection of accounts of varieties in the phenomena of the winds is given.

that the NW. winds blow oftener from November to March, and more seldom during September and October than any other months. 2. The following table is an abstract of 7 years' observations made by Dr Meek, at Cambuslang, near Glasgow :—

From this register, it appears that the NE. winds blow more frequently in April, May, and June; and the SW. in July, August, and September.* 3. These are the results of a register of the winds kept by Admiral Sir David Milne, at Inveresk, near Edinburgh, in the years 1840 and 1841.

4. By a register kept by Mr Atkinson, at Harraby near Carlisle, these

results of the wind were obtained in 1840.

Total westerly, 1324 days; total easterly, 233; calm, 56; moderate, 2481; breeze, 27; strong breeze, 13; stormy, 20.‡

5. As it is of importance for you to compare the state of the weather in the hilly with that of the low country, I shall transcribe two tables of observations made in the parish of Yarrow, Selkirkshire; the one by Mr Ballantyne, Tinnis, at an elevation of 470 feet above the level of the sea, and deduced from an average of 6 years from 1826 to 1831, the barometer and thermometer being observed at 8 A.M. and 10 P.M. :—

* Polehampton's Gallery of Nature and Art, vol. iv. p. 192-4.

† Edinburgh Evening Post, January 1842.

Jameson's Edinburgh New Philosophical Journal, vol. xxx. p. 422.

68 46 23 30 40 22 25 92 175 154 36 29.57

Summer, 53°.13

Autumn, 50°.81
Winter, 36°.89

Mean, 44°.96

and the other by Mr Alexander Laidlaw, Bowerhope, at an elevation of 560 feet above the sea, which gives these results, on an average of 10 years from 1821 to 1831.*

(375.) The direction of the winds is greatly affected by the configuration of the country, their general direction being modified so as to coincide with the natural lines of elevation and depression of the earth's surface; and it is probably on this account that the winds in Egypt are generally either N. or S.; the former prevailing nine months of the year. When the climate is tolerably regular, as in the south of Europe, the direction of the wind makes all possible difference in its character. The transition from a sirocco to a tramontana, at Rome and Naples, is as great as 10° of latitude.† A remarkable effect of local configuration on the direction of winds is thus related: "When the wind is NW. at Manchester, it is N. at Liverpool; when N. at Manchester, it is NE. at Liverpool; when NE. at Manchester, it is E. at Liverpool; and when E. at Manchester, it is SE. at Liverpool. Of course the SW. wind comes the same to both towns, as there are no hills to the S. such as are to the N. and E. of them."

(376.) The force and velocity of winds are instructive subjects of inquiry. They have been attempted to be calculated with great care and ingenuity by Mr Rouse, who constructed tables of the results. His tables

* New Statistical Account of Scotland. Yarrow-Selkirkshire, p. 30
† Forbes' Report on Meteorology, vol. i. p. 247.

Morning Herald, 19th June 1839.

have been much improved and considerably augmented by Dr Young, a philosopher of profound erudition, but whose researches are not so generally known as they should be from the condensed form of expression which he used in communicating them. He compared Mr Rouse's observations with the results of Dr Lind's scale, and constructed the following table :

TABLE OF THE FORCE AND VELOCITY OF different WINDS.

With regard to the nomenclature here given to some of the varieties of winds, a few remarks seem called for. Whatever may be the accuracy of the higher rates of velocity I cannot say, for there is no ordinary means of judging of them, except by seeing the shadows of clouds passing along the ground, but the accuracy of the smaller velocities may very easily be judged of. It is said that wind moving 2 miles an hour is "just perceptible;" and at 3 and 4 miles it constitutes what are called "gentle winds." Let us test these. Suppose the air to be perfectly calm when you are walking at the rate of 3 miles an hour, do you feel anything like a "gentle wind" blowing upon you? Are you, in fact, in the least sensible of the action of the air upon you? I think you cannot be. The air is so insensible to you in that state that you can neither hear nor feel it, and were you to stand still when it moves at the rate of 3 miles an hour, you would feel it as little. Before you feel it at all, therefore, you may safely conclude that the air is moving at a greater velocity than 3 or 4 miles an hour, whatever indication anemometers may give, for the human skin is a much more delicate instrument for this purpose than any artificial one can possibly be. On this view of the subject, Sir Richard Phillips makes these pertinent remarks: "If wind blows 100 miles an hour, that is 528,00 feet, then as water is 833 times heavier than air, water moving at the rate of 635 feet, or 1 furlong per hour, would be equal to it, which is absurd. There must be some mistake. Water at 5 miles an hour would scarcely bend a twig, whereas a West India hurricane has been known to blow heavy cannon out of a battery. Balloons have travelled 60 miles an hour, when the anemometer shewed but 8 miles." When I have observed the shadows of clouds flying over the land in a windy day in spring or summer, I have felt convinced that the wind must move hundreds of miles per hour in this country, where the velocity of wind is small compared to what it sometimes is in the Tropics. It is recorded, that such was the noise occasioned by the hurricane that took place at Pondicherry on the 29th October 1768, that when the signal guns were fired to warn the ships off the coast, their reports were never heard by the inhabitants within the fort.†

(377.) The subject of Storms, in their origin and direction, after a long period of neglect, has of late again attracted the attention of philosophers. So long ago as 1801, Colonel Capper, of the East India Company's service, in his work on winds and monsoons, gave it as his opinion that hurricanes would be found to be great whirlwinds. This

Phillips' Facts, p. 455.

† Capper on Winds and Monsoons.