mass of coal from 50 to 60 feet thick in some parts: it is composed of 5 distinct seams, separated by thin strata of stone and ironstone. This great thickness appears to have been produced by a disturbance of the strata, which has caused the series to break and overlap, or double over each other, in one part of the field. The disturbing cause was, in all probability, an irruption or protrusion of the basalt, which covers and underlies the coal.

In Hurlet coal mine, 3 miles south-east of Paisley, which has been worked for two or three centuries, the bed of shale over the coal, in the old workings, has become converted into alum slate by the combin ation of sulphuric acid, from the decomposition of pyrites with the alumine or clay. The quantity of alum is so great that a large alum work has been many years established there.

Several small coal-fields occur in different parts of the southern or transition districts of Scotland, which are entirely detached from the great coal-field we have been describing. It is deserving of notice, that the mountain limestone, which forms a boundary of the English, Welsh, and Irish coal-fields, and is abundantly developed in their vicinity, exists only to a very limited extent in the geology of Scotland.

The southern part of Scotland, extending from the English border to the coal-fields on the south of the Forth and Clyde, comprises the most fertile and best cultivated lands in Scotland; but it partakes, in a considerable degree, of the character of an alpine country; and the leading features of its geology resemble those of Cumberland, and the portion of Northumberland adjoining Scotland. Several of the mountains rise from 2,000 to near 3,000 feet above the level of the sea: the rocks of which they are composed are, for the most part, of the transition class. Greywacke and coarse slate are the most prevailing beds. Granite is considerably developed on the western side at Criffel, and in its vicinity; and, on the eastern side, the range of Cheviot Hills, composed of porphyry, forms a conspicuous feature in the country. The beds in the vicinity of these porphyritic rocks appear to have suffered considerable derangement of position by the protrusion of the porphyry. Red sandstone occurs in many of the valleys, and surrounds some of the coal-fields; but geologists are not yet agreed to what formation several of these beds belong indeed, it must be confessed, that the geology of the south of Scot land (in many parts at least) has not been examined in sufficient detail, nor in connection with each other, as a whole geological district. None of the secondary calcareous strata, that cover so large a surface in England, have been discovered in the south of Scotland, nor any vestiges of tertiary formations. The most valuable mining district that has been worked in Scotland is that of the Lead Hills, in Lanarkshire. The prevailing rock is stated to be greywacke. The veins that intersect this rock are rich in lead ores: they vary much in width: one vein, called the Susannah vein, contained a mass of ore 14 feet thick. The mines at Lead Hills formerly produced 1,400 tons of lead per annum, and those of Wanlock Head

and small, compared with those near the Forth and Clyde; but their extent and value has not yet been fully ascertained. The coal-fields at Sanquhar in Nithsdale, and near Cannonby, on the English border, have been worked several years. Coal occurs along the valley of the Tweed, and, probably, in many parts adjoining the English border which have not been yet explored. The coal in this part of Scotland must derive an increased value from its central situation, being at a distance from the great coal-fields of England, and those on the side of the Forth and Clyde. In the soil which covers the Lead Hills and Wanlock Head, a considerable quantity of gold was formerly found. In the time of Queen Elizabeth, 300 men were employed in searching for and washing the gold; and a quantity worth 100,0007. sterling is said to have been found in the course of a few years. During the last century the works were resumed; but the quantity of gold discovered was not sufficient to repay the continuance of the operations. The gold was found immediately under the vegetable soil; and was obtained by repeatedly washing the earthy matter with which it was intermixed, the gold subsiding to the bottom. Whether the sand and alluvial soil in the beds of rivers, in any other part of Scotland, have been examined in this manner, we are not informed. Gold may be obtained from the sands of rivers in most of the alpine parts of Europe, but seldom in sufficient quantity to repay the expense.

The Shetland and Orkney Islands may be regarded as an interrupted extension of the primary range, that passes through Caithness. In the Shetland Islands the rocks are much broken by the violence of the waves, and in some parts are cut into various fantastic shapes, presenting the ruins of isles now nearly obliterated. In the Orkney Islands, the primary rocks are covered in many parts by thick beds of sandstone and conglomerate.

The Isle of Man.-It may be doubtful whether this island should be classed geologically with England, Ireland, or Scotland, as it is nearly equidistant from each country: its general character resembles that of the alpine parts of the south of Scotland. From the sea, the Isle of Man presents a mountainous appearance: a group of mountains, of moderate elevation, range in a south-west and north-east direction; the highest of these is Sneafel, which is 2,004 feet above the level of the sea. From its summit, the Mourne mountains in Ireland, the Cumberland mountains, and the mountains on the south-west of Scotland, are distinctly visible. The hilly and mountainous district in the Isle of Man, which forms the greatest part of the island, is chiefly composed of slate and greywacke, containing some beds of roof slate. Low rocks of granite make their appearance in some parts of the slate district. On the southern end of the island, mountain limestone rests upon the slate, separated from it by a bed of conglomerate. The limestone extends from Poolvash to Derby Haven, a distance of about 5 miles. The northern end of the Isle of Man is nearly flat, and is chiefly composed of alluvial soil. A few veins, containing ores of lead, zinc, copper, and iron, intersect the mountains in a north and south direction: they were formerly worked;

but the workings have been abandoned several years. As might be expected from the geology of the island, no coal has been discovered in the Isle of Man: the inhabitants procure their fuel from Whitehaven.

SECT. 6. Climate.

The climate of Scotland depends upon the same physical circumstances that have been specified when treating of that of England; the chief differences between them being occasioned by the dif ferent geographical relations of the two countries. Scotland is remarkably indented by bays, creeks, friths, or arms of the sea: she has a much more limited extent of inland superficies than England, a wider expanse of ocean on the east, and is placed at a greater distance from the equator. In consequence of this last circumstance, she is more subject to cold winds from the north, to falls of snow, and to ungenial and late springs and summers, than her more southerly neighbour. But the proximity of even the more inland places to the sea, and its tempering influence, prevent snow from continuing long undissolved, and the temperature from remaining, for any very lengthened term, at the freezing point, except in the more mountainous parts. There, however, snow often lies for a very long time; and the labours of the Highland farmers are not unfrequently interrupted for two, and even three, months. Before reaching Scotland, the east and north-east winds have to traverse a wider superficies of ocean than before reaching England, so that they do not reduce the temperature so low in the former as in the latter; and heavy falls of rain more frequently come from these quarters in Scotland than in England.

Owing to these causes, the mean annual temperature of Scotland is very high for the latitude, being about 46° in places near the level of the sea. In the more southerly parts of the kingdom the climate differs but little from that of the northern parts of England. Dr. Brewster states the mean annual temperature to be 48.36 at Leith. At Edinburgh, which is elevated from 300 to 400 feet above the level of the sea, and situated about two miles from it, the annual temperature is 47.8, and this may be taken as a near approximation to that of the more inland parts of the south of Scotland: the mean temperature of winter being 38-6; of spring, 46·4; of summer, 58-2; of autumn, 48-4: the coldest month being 38-3, and the warmest 59.4.

From a long series of observations made at Gordon Castle and at Kinfauns Castle, between the latitudes 57° and 58° N., the mean annual temperature was found to be 46. At Huntly Lodge, which is 440 feet above the level of the sea, it was 45. The observations published in the Transactions of the Royal Society of Edinburgh very closely approximate to the above, and furnish the following additional

results :

St. Andrew's, on the east coast, in latitude 56° 20′, has a mean annual temperature of 46%; that of the winter months being 39·12;

At Wick, in Caithness, in latitude 58° 28′, the mean annual temperature is 4676; that of the winter months being 40-35; spring, 44·41 ; summer, 53.77; and autumn, 48.82.

At Sumburgh Head, the most southerly promontory of the Shetland Isles, in latitude 59° 52', the mean annual temperature is 4510; that of the winter quarter being 40; spring, 43.29; summer, 50-63; and autumn, 47.48.

The barometric ranges are often very great and sudden; and, as respects the British Isles especially, are evidently increased with the distance from the equator. On the southern coasts of Great Britain the range of the barometer seldom exceeds two inches; and in the more inland parts of the southern counties it is rarely so much. In the South of Scotland it is about two inches and six or seven tenths; but in the Orkney and Shetland Isles it is fully three inches.

The quantity of rain which falls on the east side of Scotland varies from 22 to 26 inches; whilst, on the west side, and in the Hebrides, it is nearly twice as much, ranging from 35 to 46 inches, according to situation. Mr. ADIE states the mean annual fall of rain at Edinburgh, for the years 1824 and 1825, to have been 23 inches, which was distributed as follows: :

Mr. DALTON assigns 37 inches as the annual fall at Dumfries; the last six months of the year being the most rainy, and each furnishing nearly an equal proportion. There is a very remarkable difference in the amount of rain that falls in one year from that which falls in another, in all situations where observations have been made. At Dalkeith, a few miles from Edinburgh, at an average of eight years, the annual fall was 22,6 inches; at Glasgow, at an average of thirty years, it was 30 inches; at Dundee, at an average of nine years, 22 inches; at Peebles, at an average of fourteen years, 28.7 inches; at Langforgan, on the Tay, at an average of twelve years, 24-5 inches; at Belmont, in Strathmore, at an average of ten years, 30 inches; at Carbeth, in Stirlingshire, at an average of eight years, 42 inches; at Mount Stewart, in Bute, at an average of seven years, 46.6 inches. Sir John Sinclair estimates the mean annual fall of rain in Scotland at 31 inches. Argyle, with its islands, has, perhaps, the most rainy climate in Scotland. Ireland is interposed between Galloway, and Ayrshire, and the Atlantic ocean; but this district is exposed, without any such protecting screen, to its entire influence. "Its lofty mountains attract the vapours that arise from the ocean, and the clouds burst in torrents upon the valleys. In the district of Cowall, and probably over the whole county, the face of the heavens is generally lowering and cloudy; a serene sky is seldom to be seen. The winds, prevented from a free circulation, rush through the glens with irresistible violence; and at the bottom of high hills, and in narrow

valleys, the transitions from heat to cold are sudden and excessive. The winters are, for the most part, mild and temperate; but the summers are frequently rainy and cold. Frosts are not intense, nor do snows lie long."-(General Report of Scotland, Appendix, vol. i. p. 123.) We are not aware that observations with the rain-gauge have been made in Orkney or Shetland; but we believe that the quantity of rain falling in them is not much under that which falls on the western coast. The truth is, however, that the quantity of rain that falls annually in any country is a very inferior consideration compared with the distribution of that quantity over the year. It is by this that the operations of the agriculturist are principally influenced, as it is this that determines the character of a climate. A great deal of rain may fall in a country; but if, like tropical rains, it mostly falls within a short space of time, as two or even three months, its climate is said to be dry; whereas a country, with a much smaller total fall of rain, but distributed over a half or two thirds of the year, is said to have a wet climate.

From an analysis of the statistical accounts of Scotland, it would appear that the average number of days in which either rain or snow falls, in parts situated on the west coast, is about 200, on the east coast about 145. And it is owing to this excess in the number of rainy days, more than to the excess in the total quantity of rain, that the climate of the western side of the kingdom is said to be wet as compared with that of the eastern side; and that it is less fit for the maturing and ripening of corn.

Winds in Scotland are influenced by the physical circumstances already explained (see sect. on the Climate of England); but they are even more variable than in England, and more boisterous, especially about the equinoxes. Westerly winds are the most prevalent, particularly during autumn and the early part of winter, but northeast winds are prevalent and severe, especially on the east coast, during March, April, and May, and sometimes part of June. High gales are generally from the west. The weather is exceedingly variable in winter and spring, particularly in the northern and western districts. The occurrence of snow, frost, sleet, and rain, with calms and high winds, in the same day, is by no means unusual. In the most northerly parts, snow generally begins to fall about the middle of November, and continues or recurs until March or April. Thick fogs, with small drizzly rains, are frequent in spring and autumn, and generally throughout the year, especially in the Western and Northern Isles, and when the wind blows from the east, In the Shetland and Orkney Isles the heaviest and most prolonged falls of rain are from the east and south-east.

The

The influence of the climate upon the vegetable productions of the country is very considerable; but much is also owing to the nature of the soil, its height above the level of the sea, exposure, &c. numerous and extensive peaty moors and morasses in hilly districts, particularly in the northern and insular parts, seem to be the result chiefly of low temperature, humidity of the air, and imperfect drainage. Some of these morasses have been formed within a com