so that pure water may be considered as able to dissolve 3 its weight of this salt. The residue of 16 ounces of the solution etches glass rapidly and powerfully.

23

The amount of solubility observed, though comparatively small, is large for a salt reputed quite insoluble, and is plainly sufficient to occasion an appreciable error in the quantitative determination of fluorine by the ordinary process, since as much as a pint of water, and that perhaps at the temperature of 212°, must often be employed in washing a precipitate of fluoride of calcium.

Memoranda regarding an Ancient Iron Boat-Hook, found in the Carse of Gowrie. By R. CHAMBERS, F.R.S.E. and V.P.S.A.Sc. Communicated by the Author.*

In the month of August 1837, some labourers employed in digging gravel on the farm of Inchmichael, in the Carse of Gowrie, found an ancient boat-hook at the depth of about 8 feet from the surface of the ground.†

This incident excited the more attention, that there was a popular notion, long prevalent, that the Carse of Gowrie was once covered by the sea, excepting only those low eminences scattered over its surface, which are supposed to have acquired the generic appellation of inches, in reference to the insulated position in which they were then placed. In support of this myth or tale, it is affirmed that the remains of an anchor were found some years ago on the estate of Megginch. Of course, no such story could be worthy of serious notice in this place, were it not for its apparent harmony with the modern geological hypothesis regarding changes in the relative level of sea and land. That the Carse of Gowrie has once been under water, no geologist can doubt; but it is a different question, has it been so submerged since the time when the British Island was first peopled, or when anchors and boat-hooks of iron came into use in this country? To set this question at rest, I took a considerable amount of trouble; 1st, to ascertain the precise local and geological circumstances of the relic, as observed at the time of its discovery; 2d, to decide whether the relic could have come into these circumstances in any other manner than by being lost in a sea formerly covering the Carse.

The

The local and geological circumstances were briefly these. boat-hook was discovered under a slightly raised piece of ground

* Abridged from a communication to the Society of the Antiquaries of Scotland, but not hitherto published.

The relic is preserved in the Museum of the Society of Antiquaries in Edinburgh.

near the extremity of the mount called Inchmichael. The Errol station of the Perth and Dundee Railway has since been set down within 50 yards of the spot. From pits still open, it can be observed that the ground is here composed to a considerable depth of gravel, with an appearance of stratification; and this gravel is continued all the way to the end of Inchmichael, which is a mass of the same material. The place is a mile from the estuary of the Tay. The general surface of the argillaceous plain called the Carse, is here 25 feet above tide; but the particular spot where the boat-hook was discovered, is three feet higher, or 28 in all; consequently, the boat-hook was deposited fully 20 feet above the present level of the sea. The relic itself was in no respect uncommon in its appearance. It was pronounced by Rear-Admiral Sir Adam Drummond of Megginch, to be such an instrument of its kind as would be used in a man-ofwar's launch, or a mercantile boat of three or four tons. The appearance of the hose gave reason to suppose that it had been fastened in the usual way to a wooden shaft.

I may here remark, that the antiquary makes at the first a decided objection to a very great antiquity for any relic of iron. It is now ascertained that, over all Europe, human society existed for ages without any knowledge of metals, that there succeeded an age in which copper hardened by an infusion of tin (bronze), was used for making implements, and that not till these two long periods had elapsed, and not till a time verging upon the historical era in our country, was the use of iron introduced. It is therefore certain, that this boat-hook could not have been lost or embedded at this place in one of the earliest ages of a Caledonian population. It hence becomes the more desirable to ascertain if the existence of the relic in such a situation, could not be accounted for without supposing any great geological change as occurring subsequently to its deposition. We might of course assume, with tolerable confidence, that the article is comparatively modern; yet there must obviously be some satisfaction in knowing by what means a nautical implement had probably been embedded at so great a depth in stratified gravel, a mile from the present shore.

One important feature of the Carse in this district is now to be adverted to, namely, a trench or ditch in which a little rill crosses the plain obliquely, to join the estuary in one of those creeks locally called pows. The course of this rill is not more than 150 yards from the spot where the boat-hook was discovered. It is, in these days of high cultivation, a narrow ditch of well-defined sides; but no one can doubt that, in other times, it would comprehend a wider space. Now the bottom of the ditch at this place, is so little above the level of the sea, that an abnormal tide might reach it-though I am not aware of any such event having been actually observed. us look, however, to the records of such events in early times. Sir Charles Lyell, in his Principles of Geology, adduces a number

Let

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of historical notices of inundations by the sea in Holland, causing the destruction of vast numbers of human beings and cattle, and in some instances permanently changing the face of nature. The extreme lowness of that country makes it little surprising that many such calamities should have taken place; but we are less prepared to hear of a tract 25 feet above the sea-level, and that not fronting the open sea, but bordering a confined estuary, being on any occasion submerged. It does nevertheless appear as if the sea had actually, on several occasions during the middle ages, covered large portions of the coast in this part of Scotland, as well as in other districts of the island. The Saxon Chronicle states that, in 1014, on the eve of St Michael's day, came the great sea-flood which spread wide over the land, and ran so far up as it never did before, overwhelming many towns, and an innumerable multitude of people." Fordun describes the great flood of 1212, by which ancient Perth is understood to have been destroyed. He speaks of great river floods being on this occasion driven back by the swelling of the sea, and the waters being thus raised so much above their usual level, that not merely boats and cobles, but large ships were carried up into the streets and highways. As this was probably only a river flood overspreading the comparatively low grounds beside the Tay, near its junction with the Almond, we cannot with confidence suppose that it could have any effect upon the Carse of Gowrie; there is more likelihood of such effect from the sea-flood, commemorated by the same author as taking place in 1267, when, on the day of the eleven thousand virgins, a very great storm arose in the north; by which the sea, being roused to fury and overstepping its usual bounds in a wonderful manner, levelled houses, towns, and trees, and brought the greatest damage in many places, but particularly between the Tay and the Tweed. The chronicler says, that such a flood had not happened from the time of Noah; and adds, that its effects are still visible in his own day, upwards of a century and a half from its Occurrence. Matthew of Westminster adverts to several inundations of the 13th century, as producing extensive damage. One on St Martin's eve, in the year 1236, was attended by a constant rise of the sea during two days and a night, the strength of the wind preventing its reflux. It carried ships with breach of anchor out of harbours, broke down shores, and destroyed a multitude of people. An occurrence in 1256, similar, except in there being no mention of the sea, is worth quoting on the present occasion, as the author states that bridges, hay-stacks, the dwellings of fishermen, with their nets and boat-spears, and even children in their cradles were carried away.

With such events as these on record, within the period during which iron implements have been in use, it does not appear very difficult to account for the loss and embedding of the Inchmichael boat-hook, without calling any greater geological forces into operation in the case. We may suppose the sea-flood of 1267 to have borne a small

vessel or boat to this place, favoured in doing so by the natural hollow of the rill formerly adverted to. The beating of the inundation on the skirts of Inchmichael might produce that bedding of gravel in which the relic was subsequently found. As the same quasi-valley passes through the neighbouring estate of Megginch, it seems far from unlikely, that the anchor found in a low situation there may have belonged to the same vessel with the boat-hook. All this is of course purely hypothetical; but our purpose, it must be remembered, is only to discover a manner in which the loss and deposition of these articles might have occurred, since the present relative arrangements of sea and land were assumed.

sea.

On a former occasion, I enumerated a series of similar discoveries in the low sea-bordering lands of Scotland. The remains of a boat, and several nautical implements, particularly an anchor, are recorded to have been found in the Carse of Falkirk, several miles from the In the Carse of Stirling, as is well known, the skeletons of two whales have been discovered in recent times, in each case accompanied by an implement of bone, denoting that the animals had been embedded there since the country was inhabited by man. In the similar plain on which part of Glasgow is built, four or five ancient canoes have been discovered; and, in one case, a flint weapon was found within the boat. Considering that the ground at Glasgow was 25 feet above the sea, while the utmost ascertained height of modern inundations in the Clyde is 21 feet, I leant, though not without due hesitation, to the hypothesis, that a change in the relative level of sea and land was required to account for these phenomena. I must now acknowledge, that the archæological considerations regarding the Inchmichael boat-hook, and those connected with ancient inundations and abnormal tides, dispose me to regard the whole phenomena as of a purely historical character.

On the Causes which Influence the Changes of Isothermal Lines. By Mr RICHARD ADIE. Communicated by the Author.

In the following communication, I mean to endeavour to shew, that the high temperature enjoyed by European countries, when compared with others in the northern hemisphere of the same latitude, can be better accounted for when the cause of the elevated temperature is referred to heat generated in the great desert of North Africa, than when, as is more generally done, it is attributed to the influence of the gulf stream.

For isothermal lines, or lines traced through places on the earth's surface, having the same mean annual temperature, we are indebted,

as the readers of this Journal are well aware, to M. Humboldt. This philosopher has traced in the northern hemisphere eight such lines, five of them confined chiefly to the opposite shores of the Atlantic, and three of them extending round about two-thirds of the earth's surface. The evidence given by these lines, together with the recent maps of monthly isothermal lines by Professor Dove, shew the north-western parts of Europe to possess a much milder climate than any other localities of corresponding latitude in the same hemisphere.

M. Humboldt found, that of two stations of equal latitude, the one in Europe and the other in North America, the mean temperature in the former was 41 of Fahrenheit above the mean annual temperature of the latter. The attempts which have been made to explain the reason of this great elevation of temperature in Europe have dwelt chiefly on the proximity of the Atlantic, and the influence of the gulf stream. In so far as the western shore of a continent has been shewn to be warmer than the eastern, the proximity of the Atlantic would be available to explain the superior temperatures in Europe, compared with the United States or British possessions in North America. But, if the observations which have been made on the western shores of North America can be relied on, the shore of that continent, bordered by the far-stretching Pacific, has much lower temperatures than similar latitudes in Europe, north latitude 45° being on the same isothermal line with London between 52° and 53°. Consequently, after deducting what is due to a western sea-board, there still remains an excess of temperature in Europe to be accounted for. The gulf stream which, after a course of about 4000 geographical miles, passes along the coast of the United States to the banks of Newfoundland, where it begins to cross the Atlantic to the shores of Norway, has been repeatedly urged as a reason for the high temperatures of Europe; if we look at the registers of temperature of places on the North American coast, near the banks of Newfoundland, we find them but slightly elevated by that cause, while on the coast of Norway, where the gulf stream can have far less influence, the temperature for the latitude is very great, hence another source of heat is required to account for the elevated temperatures of north-western Europe. At a distance, varying according to the localities from 1500 to 3000 geographical miles, there is in the Sahara of Africa a magazine of heat, usually considered as the greatest on the face of the globe, and composed of heated air capable of travelling with facility at ten times the velocity of oceanic currents of water.

The air on the African desert has usually the same direction as the trade-winds, namely, north-easterly, which is now admitted to be explained by the reasons given by Halley, namely, the influence of the sun rarifying the air at the equator, and the rotation of the earth on its axis. The prevailing winds of the desert taking away