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3. The air near the surface of the earth is warmer than it is in the region of the clouds. The higher we ascend from the earth the colder do we find the atmosphere. Hence the perpetual snow on very high mountains in the hottest climate.
Now, when, from continual evaporation, the air is highly saturated with vapour, though it be invisible and the sky cloudless, if its temperature is suddenly reduced by cold currents descending from above, or rushing from a higher to a lower latitude, or by the motion of saturated air to a cooler latitude, its capacity to retain moisture is diminished, clouds are formed, and the result is rain. Air condenses as it cools, and, like a sponge filled with water and compressed, pours out the water which its diminished capacity cannot hold. How singular, yet how simple, the philosophy of rain ! What but Omniscience could have devised such an admirable arrangement for watering the earth!
By inspiration given;
To guide our souls to Heaven.
In this dark vale of tears,
And banishes our fears.
Of life shall guide our way,
Of Heaven's eternal day.
THE ROCKING STONE, FALL RIVER, The Needle Mountain iu Dauphiny, described as erratic, is a thousand paces in circumference at the top, and two thousand at the base. Near Neufchâtel a mass of granite occurs, forty feet high, fifty long, and twenty broad, estimated to weigh 3,800,000 pounds. On the Jura limestone mountains, at an elevation of 2000 feet above the Lake of Geneva, there are granitic blocks, the solid contents of which amount to 1200 cubit feet upon the Salere, to 2250 on the Côteau de Boissy; and the block called Pierre à Martin is mentioned by Mr. Greenough as containing even 10,296 cubic feet. The rock in Horeb, from which, according to monkish tradition, the leader of Israel miraculously drew water, is a mass of granite, six yards square, containing 5823 cubic feet, lying upon a plain near Mount Sinai. In the United States, boulders occur of equal dimensions. “On Cape Awn, and its vicinity," says Dr. Hitchcock, "I have not unfrequently met with blocks of sienite not less than thirty feet in
diameter; and in the south-east of Bradford county, I noticed one thirty feet square, which contains 27,000 cubic feet, and weighs not less than 2310 tons. In the west part of Sandwich, near Cape Cod, I have seen many boulders of granitic gneiss, twenty feet in diameter, which contains 8000 cubic feet, and weigh as nuuch as 680 tons. Two graywacke boulders of the same size lie a few rods distant from the meeting-house in Norton, in Dr. Bates's garden. A granite boulder of equal dimensions lies about half a mile south-east of the meeting-house in Warwick; and one of similar dimensions lies on the western slope of Hosac mountain, at least 1000 feet above the valley over which it must have been transported. One of granite lies at the foot of the cliffs at Guy Head, on Martha's Vineyard, which is ninety feet in circumference, and weighs 1447 tons. At Fall River there is a boulder of conglomerate which originally weighed 5400 tons. But the instances are endless that might be given of similar large and insulated masses, now lying at a remote distance from the parent rocks from which they have been abstracted. Wandering in the southern extremity of America, Mr. Darwin speaks of his course being obstructed by wellrounded pebbles of porphyry, mingled with immense angular fragments of basalt and of primary rocks, nearly seventy miles apart from the nearest analogous mountain ; while in Europe the vast plains of Prussia, Poland, and Russia, comprehending a zone of country nearly 2000 miles long and from 400 to 800 miles wide, are strewed with Loose detritus and crystalline blocks of colossal size, all of which have been transported from the mountain masses in Scandinavia.
A huge block of drift stone in Pembrokeshire has long puzzled tourists and antiquarians as to its origin. It is mounted on three low rocky peaks, and has all the appearance of having been so placed by human agency. But considering its immense size, and the chances in favour of such a deposition under the occasional circumstance of the diluvian period, it is probably a work of nature, and in no sense a monument of the Druids.
But the mystery of these rocking and strangely poised rocks, is in a measure solved by the fact noticed by observers of the granite masses of Silesia, and the Swiss Alps, namely, that at the time the rocks were deposited in the spots where we now find them, they rested on broad foundations, but that decay has proceeded faster in one part of the stone than in another, and hence their balanced condition is the work of time. A great number of examples occur round the islands of Scotland, of huge masses of granite having been worn away, and separated into fragments, by the action of the sea ; and in the case of the Bullers of Buchan, numerous arches and caves have been produced, into which the sea rushes with strange noises and repeated echoes. The summit of Mount Bennachies supplies an example of the manner in which granite yields to the decomposing power of the atmosphere, having been separated into huge masses or blocks, irregularly piled, by the mouldering away of the base. This crumbling of rocks at the base explains very readily the secret of such instances of poised blocks as that afforded by the Logan Stone, near the Land's End, in Cornwall. This is an enormous mass of granite so delicately balanced that the strength of one man was, till recently, sufficient to set it in motion, " This far-famed rocking-stone,” says Mr. Collins, in his recent work, entitled “Rambles beyond Railways,' “rises on the top of a bold promontory of granite jutting far out into the sea, split into the wildest forms, and towering precipitously to a height of a hundred feet. When you reach the Logan Stone, after some little climbing up perilous-looking places, you see a solid irregular mass of granite, which is computed to weigh eighty-five tons, resting on its centre only, on a flat, broad rock, which, in its turn, rests on several others stretching out around it on all sides. You are told by the guide to turn your back to the uppermost stone ; to place your shoulders under one particular part of its lower edge, which is entirely disconnected, all round, with the supporting rock below; and in this position to push upwards slowly and steadily, then to leave off again for an instant, then to
push once more, and so on, until after a few moments of exertion, you feel the whole immense mass above you moving as you press against it. You redouble your efforts, then turn round and see the massy Logan Stone, set in motion by nothing but your own pair of shoulders, slowly rocking backwards and forwards with an alternate ascension and declension, at the outer edges, of at least three inches. You have treated eighty-five tons of granite like a child's cradle ; and, like a child's cradle, these eightyfive tons have rocked at your will !”
It is not so easily moved as formerly, owing to a slight decay of the protrusion of its base which formed the pivot of its motions. Six-and-twenty years ago it was overthrown by artificial means, and then lifted again into its former position.
The Land's End is a curious rocky headland, forming the extreme westward boundary of the British coast. Mr. Collins, from whose delightful book we quote again, thus describes it
“I have already said, that the stranger must ask his way before he can find out the particular mass of rocks, geo