explanation of drift must combine the actions of all. One of these, namely, the simple action of the tidal current, seems scarcely to have been noticed in reference to this subject, though it has, doubtless, co-operated materially in producing some of the results observed. Almost every bay on our coast may afford evidences of the accumulation of gravel and sand by tidal currents; and it is very curious to observe how the shingle, or marine gravel, is sometimes moved over a smooth surface of sand. Nor is this the only effect, as I was enabled to observe, to great advantage, the action of the moving gravel in producing grooves in more solid substances, as exhibited in the breakwater at Southsea Castle, near Portsmouth, which has been worn in the most remarkable manner in deep parallel grooves, so as to assume the appearance of the most complicated mouldings. I have no doubt that a similar grooving takes place in ordinary rocks when favourably situated as regards the tidal current; and I would, therefore, suggest to every observer of such phenomena the inquiry, whether the grooving, as regards its physical position, is most nearly in relation to the action of a land glacier or to that of tidal currents. Nor must fluviatile action be overlooked, as its power is very great under fitting circumstances. For example, can it be doubted that such a river as the St Lawrence must, both by its waters and by the masses of ice it bears along upon them, convey large quantities of detritic matter, and arrange that matter at the bottom of the lakes in a manner very similar to that observed in the drift of our plains and estuaries. Other evidences of fluviatile action in pot-holes, &c., as pointed out by that eminent American geologist, Professor Hitchcock, should not be overlooked. On solid rocks the action of rivers is small, but on the softer secondary strata, and on drift, it is considerable. In these latter cases they are modifying agents, removing and readjusting ancient drift, so that it is to more ancient rivers, or more ancient causes generally, that we must ascribe the drift itself. In making our selection between these causes we must not forget that a mere present difference of level between the point observed and the bottom of the valley or the stream running in it, is not a sufficient reason for rejecting the evidence of glacier action, as subsequent elevation has, doubtless, raised up the whole. In the glacial period when, as it is presumed, this extension of glaciers occurred, it is highly probable that our mountains were less elevated, whilst the limit of eternal snows was brought nearly to the level of the ocean. If, then, I consider a glacier as a true motive power applied by nature to transport drift, I consider it only as one power among many. I look upon it also as auxiliary to other glacial agencies, as it is the carrier by which detritus is conveyed from the mountain top and valley, until it is confided to the iceberg or icefloe, to be floated away to other and distant regions; but even with these restricted views of the geological agency of ice, it is evident that our knowledge of the phenomena connected with it cannot be too much extended; and I am happy, therefore, to see that it continues an object of zealous research. On the Remains of Druidical Temples near Penzance. By RICHARD EDMONDS, Jun., Esq.* Having in former communications described the dwelling places, and tombs of the very ancient inhabitants of this. neighbourhood, I will now speak of their Temples-those erections which consisted originally of nineteen detached stones, placed upright, from 3 to 5 feet above ground, in rude circles, varying in diameter from 65 to 80 feet, and called by antiquarians" Druidical Temples," but by the neighbouring population" nine maidens," an abbreviation doubtless for "nineteen maidens." Borlase has noticed four of these within 5 miles of Penzance, all of which are still to be seen.t (Here the author minutely describes the four temples.) These four temples are not the only ones in Britain wherein the number 19 stands so prominent. In Stonehenge the inner oval immediately around the altar consisted of precisely * Vide Penzance Natural History and Antiquarian Society's Report for 1850. Antiq., p. 181. nineteen stones (see the plate in Dr Stukeley's Stonehenge, p. 20). So, too, the temple of Classerniss, in the isle of Lewis, "called a heathen temple," consisted of an avenue of nineteen stones on each side leading into the circle of twelve others.* I will now cite a passage from Diodorus Siculus,† in support of the general opinion that these circles were temples of the sun. The passage begins with an apparent reference to Mount's-bay, the most southern and the mildest part of Great Britain, and the only place in this island considered to have been frequented by the ships of the Phoenicians and Greeks: "Amongst them that have written old stories much like fables, Hecatæus, and some others say, that there is an island in the ocean over against Gaul (as big as Sicily) under the arctic pole where the Hyperboreans inhabit; so called because they lie beyond the breezes of the north wind-that the soil here is very rich, and very fruitful; and the climate temperate, inasmuch as there are two crops in the year." That Mount's-Bay is the place alluded to by the Grecian author, may be inferred from the fact of its still producing much earlier, and therefore more crops in the year than any other part of Britain. But to proceed with the passage from Diodorus: "They say that Latona was born here, and therefore that they worship Apollo above all other gods; and because they are daily singing songs in praise of this god, and ascribing to him the highest honours, they say that these inhabitants demean themselves as if they were Apollo's priests, who has there a stately grove and renowned temple of a round form, beautified with many rich gifts: that there is a city likewise consecrated to this god, whose citizens are most of them harpers, who playing on the harp chant sacred hymns to Apollo in the Temple, setting forth his glorious acts." "The sovereignty of this city, and the care of the temple (they say) belong to the Boreades, the posterity of Boreas, who hold the principality by descent in a direct line from that ancestor." * Borlase's Antiq., p. 190. † Book ii., chap. iii. Booth's Translation, p. 139. The city and temple here referred to are supposed to have been those of Old Sarum and Stonehenge, and to have been erected under the superintendence of the Druids who came to Mount's-Bay from Canaan in Tyrian ships, and were received as priests by the aborigines of this island. The Druidical temples, however, in the neighbourhood of Penzance, being of much ruder construction, and formed of unhewn* stones, are considered still more ancient than that of Stonehenge, and to have been erected by Druids who had migrated from Canaan before the Jewish temple was built, and when the Jews had only their tabernacle, the court of which, where the victims were slain, being, like our Druidical temples, all open to the sky, and inclosed by pillars placed at distances of 5 cubits, or about 9 feet from each other, the object in each case being apparently to exclude all who were not especially engaged in the sacrifices, and at the same time to allow the people on the outside to behold what was transacting within; for the Jews believe that the victims were slain in sight of all the congregation, and as the court could not hold a tenth part of the congregation, it seems probable (Scripture being silent on the point) that the pillars from which the curtains (5 cubits in breadth) were suspended, were, like those of our Druidical temples, sufficiently low to allow the people to look over them. The circular forms of the latter might be traced to the worship of the sun. It is also to be observed, that the Druidical priesthood resembled that of the Jews, in being confined to the descendants of one man, as recorded in the quotation. The passage, after mentioning that the Hyperboreans used "their own natural language," and had "of long and ancient time a special kindness for the Grecians," concludes with the following statement:-"They say, moreover, that Apollo once in nineteen years comes into the island, in which space of time the stars perform their courses and return to the same point, and therefore the Greeks call the revolution of nineteen years the Great Year." This mythological reference to the cycle of nineteen years, *Ex. xx., 25. at the end of which the new and full moons happen on the same days of the year as they did at the beginning, is very remarkable, for by it Christians have always ascertained the days of their movable festivals, and the Greeks adopted it for the like purpose in 433 B.C., Meton having obtained the first prize at the Olympic games for its discovery. Now Meton may have derived it through Hecatæus from Britain, as above-mentioned, and the British Druids may have had it from the Jews, whose year in the time of Moses consisted, like our own, of 365 days, and whose great festival of the Passover was (like ours of Easter) regulated by the moon. It is, I imagine, to this cycle of nineteen years that the number 19, so prominent in our Druidical temples, refers. On the Constitution of the Atmosphere. By M. LEWY. The memoir which I have the honour to submit to the Academy contains the results of a series of researches on the constitution of the atmosphere, executed between France and New Granada, and from the coast up to 3193 metres above the level of the sea. The analyses were performed by the new process of M. M. Regnault and Reiset, which consists, as is well known, in analysing the air by volumes. To measure the elastic forces of the gas I employed an excellent cathetometer, constructed by M. Perraux. The process thus combined enables us to obtain much greater precision than has hitherto been reached in this class of experiments. To judge of the degree of accuracy attainable, it suffices to examine the numerical details of two analyses; and it will be seen that the greatest difference between two analyses made with the same specimen of air never exceeded rooth, and most frequently was not. more than 100,booth. The various specimens of air which I analysed were collected in bulb tubes with the two ends drawn out and open; the capacity of these tubes was about 100 cub. centims. The air was collected in the following manner: one of the extremities of the tube was connected by means of caoutchouc |