sideration deserves especially the attention of travellers, who can seldom, at one place, mark the temperature of the air for any length of time, without which, any observations at all are comparatively of little moment, but who might, nevertheless, add greatly to our information, by a few judicious experiments on the temperature of the ground. It is on this account, that observations of the temperature of springs are so valuable,—of those springs particularly, whose waters flowing from a considerable depth, carry the temperature of the interior along with them to the surface; and there affect the thermometer exactly, as if itself had been sunk in the ground. On many springs of this kind, accordingly, the vicissitudes of the seasons have scarcely any influence. We have frequently noted the temperature of a spring near the top of the Lammermuir hills in Haddingtonshire. It scarcely varies 1° throughout the year, and the celebrated fountain of Vaucluse only varies 29.1, rising to its highest temperature 56.3 in the beginning of September, and falling to the lowest 54.1 at the beginning of April. *

The nature of the ground, and even of the mere surface, has, it appears, a sensible influence on the thermometers that are sunk in it, and a knowledge of this circumstance might often be of practical utility. In the laying of water pipes, for example, or storing up of vegetables, it would indicate how far they should be sunk to be quite beyond the reach of frost. By measuring the difference between the temperature of the air, and that of the ground, at the same time, Mr Leslie finds, that "while fresh ploughed land, for instance, indicates an increased temperature (above that of the air) of 8o, a grass plot, close beside it, will scarcely show a difference of 3°. Nor is this distinction owing to any greater absorption of light by the black mould; the reflection from the surface, in both cases, being extremely small. A thin layer of hay, whether spread on the naked soil, or on the green turf, will betray the same diminished effect. The fibres of the grass exposing a multiplied surface to the contact of the air, the greater

portion of the heat is hence dissipated before accumulation. A corresponding effect has been remarked with respect to the impressions of cold. Thus, in the neighbourhood of Edinburgh, after a long tract of rigorous weather, the frost was found to have penetrated 13 inches into the ground in a ploughed field, but only 8 inches in one piece of pasture ground, and 4 inches in another. But, in some of the streets of that city, the frost had descended even below two feet, so as to begin to affect the water pipes. The greater density and solidity of the pavement had, no doubt, conducted the frigorific impressions more copiously downwards, while the loose and spongy blades of grass had mostly scattered and wasted those impressions in the open field. This consideration, it is obvious, might lead to very important practical results."*

The above experiments, while they show clearly the progress of the sun's heat downwards, afford, so far as they go, no indication of any permanent increase as we descend, or of any permanent heat rising from below,―no sign of the supposed existence of a central fire; but a very considerable heat might, no doubt, exist at the centre of the earth, and yet be quite insensible at so sinall a depth below the surface, and for so short a period as any experiments have been conducted. It would be extremely interesting, therefore, to obtain observations at greater depths at the bottom, for example, of the deepest mines. It is certainly most natural to regard the sun as the only original source of heat; that which appears in the phenomena of volcanoes and boiling springs, being only what the earth has already received from this source, redeveloped, and this too but very partially, by processes as yet unknown, but similar probably in principle to those with which we are familiar. More decisive experiments, therefore, at great depths, would probably throw light on this curious subject. The theory in which the earth is supposed to receive all its heat from the sun, and to retain all that it receives, if it were established, would lead to important results. If heat be gradually accumulating on the earth, then must it have been increasing for ages, and

there may even have been a time when its intensity was very feeble, or when the cold was severe beyond any thing we at present experience, or can even conceive. Would not this circumstance, then, point more than any other to the origin of these extraordinary revolutions which have taken place on the earth's surface? The materials which at present compose this surface have evidently not been thrown together at random. They are arranged in regular masses or rocks, each of them distinguished by very peculiar properties, and the whole system bearing evident marks of design, and of the operation of a great cause at once over the whole globe. The more studiously, in short, these singular masses are examined, the more clearly do they evince, on the whole, a slow, regular, and successive formation. What power in nature then are we acquainted with, so likely to have operated on this vast scale, and formed these universal depositions as that of heat, the living principle of the organised world? not, indeed, by any sudden and violent efforts, but by its slow, regular, and continued accumulation. From what we already know of this active fluid, some idea may be formed of the changes which would arise on the earth, if we should conceive it gradually to be withdrawn. The ocean would become a solid rock, -the present race of animals would disappear, the atmosphere itself might become liquid, and, together with other fluids now aerial, might form the occan of this imaginary world. If these bodies, in their present gaseous form, are many of them distinguished by their highly solvent power, with what augmented energy would they not operate in this state of concentration; and as the present ocean dissolves salts and other bodies, might not this new element render fluid many of the hardest rocks? If the diminution of heat, therefore, would thus change the face of the globe, might not, on the other hand, its gradual accumulation produce the reverse changes, as they appear, from existing records, really to have taken place? Crystallization seems to have been the immediate agent in the formation of the present rocks, and might not, therefore, the gradual increase of heat, while it dissipated the more volatile principles of the fluid element into

---

air, have turned, at the same time, the more fixed ingredients into earth, and thus deposited those regular and crystalline masses that we observe? Such are the speculations which this view of the system of nature would suggest. But on so obscure a subject though knowledge is undoubtedly on the advance, we shall yet probably remain long in ignorance, if, indeed, it be at all given to human genius ever to solve so hidden a mystery,-ever to develope, as it has already done in the heavens, the great revolutions which are proceeding, perhaps, with equal regularity on the earth." About such ultimate attainments," in the language of a very celebrated philosopher, when speaking of the discovery of a principle yet more general than gravitation, "about such ultimate attainments it were unwise to be sanguine, and unphilosophical to despair."

SCOTTISH ZOOLOGY.

No. III. †

II. Order.

GLIRES. (Gnawers.)

THE animals of this order are dis tinguished from those of the preceding, termed Fere, by the absence of tusks. Their incisors, limited to two in cach jaw, are remarkable on account of their great length and sharpness. In some, these incisors are simple, but in others, behind each incisor in the upper jaw, there is a subsidiary one, sinaller in size and not so long. Between the incisors and the grinders there is a vacant space. The grinders differ in their form according to the genera, having the top either flat with transverse ridges, or uneven and tuberculated. The food of the quadrupeds of this order consists chiefly of vegetable matter, as grain, roots, and even wood, which they speedily reduce by cutting with their incisors. In the following arrangement of the genera, the divisions appear to us more natural and definite than those which Cuvier has adopted.

This species is not uncommon in England. In Scotland, however, it is rare, and does not appear to have been observed by any other naturalist than the late Dr Walker, who inserts it in his Mammalia Scotica, without specifying the place where it was found.

II. Tribe. Summits of the grinders uneven, being covered with small eminences of enamel. The animals of this tribe feed on a greater variety of substances than those of the preceding.

XVI. Genus.-Mus. Mouse. Grinders three in each jaw; tail about the length of the body, annulated with scales and thinly covered with hair.

a. Mice.

27. M. musculus. Common Mouse. Fur yellowish brown above, mixed with black hairs; beneath iron grey. Body about three inches in length. G. Luch.

The mouse is common in houses, in all districts of the country. It is very prolific, breeding several times in the course of the year. We have found seventeen young ones in a nest, all nearly of the same size, and blind. A beautiful variety sometimes occurs, with red eyes and white fur,

28. M. sylvaticus. Field Mouse. Fur yellowish brown above, beneath white; the margin of the former colour and a spot on the breast ferruginous. Length of the body about four inches and a quarter. Weight one ounce. Tail black above, beneath grey, and of the same length as the body.

Sibbald refers to this species in his Scotia Illustrata, p. 11, lib. iii. p. 12. But Ray is the first British author who has described it with accuracy, in his Syn. An. p. 218, under the title

Mus Domesticus Medius.

The ears are larger, the head longer, and the eyes more prominent than in the common mouse. This species never frequents houses. It inhabits the fields, and in gardens is equally destructive as the field campagnol. It forms its retreat under ground. It brings forth nine young ones at a litter. It lays up a store of seeds and roots before winter, and in cold weather, when the air is about eleven de

grees above the freezing point, it be comes torpid,

29. M. messorius. Harvest Mouse.

Fur chestnut brown above, white beneath; the colours divided by a straight line. Length of the body 24 inches, and of the tail 2 inches. Weight one-sixth of an ounce.

The late Mr White of Selborne discovered this species in Hampshire in 1767. From his observations, Mr Pennant appears to have drawn up his description in the Brit. Zool. I. p. 121, without acknowledging the source of his information. According to Mr White," they never enter into houses; are carried into ricks and barns with the sheaves; abound in harvest; and build their nests amidst the straws of the corn above the ground, and sometimes in thistles. They breed is many as eight at a litter, in a little round nest composed of the blades of grass and wheat." White's Works, I. p. 59.

We are not certain that this species has ever been found in Scotland. Perhaps it is not specifically distinct from the field-mouse, which varies considerably both with regard to size

and colour.

30. M. rattus. Black Rat. Fur greyish black above, paler coloured and of the tail nine inches. S. Black beneath. Length of the body eight, rotten, Roof rotten, G. Radan.

This is a voracious animal, living in houses, and devouring all sorts of provisions. We have evidence of their bringing forth eleven young ones at a litter, and of their pulling the hair off the necks of cows to line their nests.

It is generally supposed that this the brown rat, which is considered as species is now nearly extirpated by its enemy. We, however, not only want evidence of the enmity subsisting between the species, but we know same house; the brown rat residing that they have lived for years in the in holes in the floor, the other in the roof. We fear that the period of their infest the older houses of London and extirpation is far distant. They still Edinburgh, and in many districts of the country they are very common.

31. M. decumanus. Brown Rat. Fur above, yellowish brown, beneath grey. Tail equal in length to the

body, which is about nine inches. E. Norway-rat; S. Grund-rotten.

This species appears to have been introduced into this country about the middle of last century. Although not so nimble as the black rat, it is stronger and bolder; the nose is more obtuse, and the hair on the feet thinner. It forms its holes under ground, and prefers being near drains of foul water. It swims and dives with ease. It brings forth as many as nineteen at a litter.

XVII. Genus.-SCIURUS. Squirrel. Grinders, four in each jaw, with a small temporary one in front in the upper. Incisors much compressed; tail brushy.

32. S. vulgaris. Common Squirrel. Fur above, brownish red, beneath white; ears tufted with long hairs. Length of the body about eight inches. G. Feorag.

The squirrel is common in the wooded districts of the middle and south of Scotland. It resides on trees, feeding on buds, twigs and fruits. It heaps up a stock of provision for the winter, securing it in the cleft of an old tree. It makes its nest in a similar situation, and brings forth four or five young ones, which are easily tamed. About thirty years ago, squirrels were rare in Argyleshire, in those woods where they had abounded some years before.

The hare has its form on the surface of the ground. It breeds three or four times in the season, goes with young thirty days, and brings forth from one to five at a litter. The young ones have their eyes and ears open, and their bodies covered with fur. The flesh of the hare is much sought after, although of a dark colour. The skins form a considerable article of trade. They are collected who sell them, sometimes to the in the country by itinerant dealers, amount of thirty thousand, in the February market at Dumfries.

34. L. variabilis. Alpine Hare. Ears shorter than the head, and black towards the tips, the rest of the body dusky in summer, and white in winter. Weight about six pounds. S. White hare, G. Maigheach gheal.

This hare is confined to the high mountains of the north of Scotland. It is seldom found lower than 2000 feet above the level of the sea. It makes its retreat beneath stones, or in crevices in the rocks.

35. L. cuniculus.

Rabbit.

Ears

shorter than the head, dark coloured towards the tips. Tail, above, nearly of the same colour as the back. E. Coney. S. Kinnen.

The rabbit is common in Scotland and the islands. It lives under ground, breeds six or seven times in the year, and brings forth six to The young are eight at a litter. blind, deaf, and naked at birth. The flesh of the rabbit is white and tender, the fur thick and valuable.

There are three varieties found in Scotland. The first is the grey-rabThe second bit, common in warrens.

is the black-rabbit. These are found in various warrens, but are no where numerous. The third is the Angora rabbit. This is found on the Isle of May in small numbers. These do not associate with the common kind, but live and breed in holes apart. They even refuse to procreate with the common kind. The fur is of a dirty ash colour above, paler beneath, and in some specimens three inches in length, and of a silky fineness. It is not known at what time, or for what purpose, this variety was here introduced.

3 T