or three eruptions while we were close to it; seve"ral of the red-hot stones rolled down the sides of "the cone, and bounded a considerable way beyond 66 us. The base of the cone is the lowest part of the "island, and very little higher than the level of the "sea. It arises with an acclivity of 32° 17′ to the height of 1800 feet nearly, which is also the elevation of the other parts of the island.

"From its present figure it may be conjectured "that the volcano first broke out near the centre of "the island, or rather towards the north-west; and "in a long process of time by discharging, consuming, and undermining, has brought it to the pre"sent very extraordinary form, of which a very cor"rect drawing by Lieutenant Wales, will impress a "distant idea.

66

"Those parts of the island that are distant from "the volcano, are thinly covered with withered shrubs " and blasted trees. It is situated in latitude 12° 15′ "north, and fifteen leagues east of the northernmost "island of the Archipelago*, and may be seen at the "distance of twelve leagues in clear weather. A quarter of a mile from the shore, there is no ground "with 150 fathoms of line."

REMARK.

From the very singular and uncommon appearance of this island, it might be conjectured that it has been thrown up entirely from the sea, by the action of subterranean fire. Perhaps, but a few centuries ago, it had not reared itself above the waves; but might have been gradually emerging from the bot tom of the ocean long before it became visible; till

* The easternmost cluster of the Andaman Islands.

at length it reached the surface, when the air would naturally assist the operation of the fire that had been struggling for ages to get vent, and it would then burst forth. The cone or volcano would rapidly increase in bulk, from the continual discharge of lava and combustible matter; and the more violent eruptions which might have ensued at times, when it would throw up its contents to a greater elevation and distance, might have produced that circular and nearly equidistant ridge of land we see around.

If this conjecture should gain credit, we may suppose not only many islands, but a great portion of the habitable globe, to have been thrown up by volcanos, which are now mostly extinguished. Many hills and islands now clothed with verdure, bear evident marks of having once been in this state. A ground plan of Barren Island would so exactly resemble some of the lunar spots, as seen through a good telescope when their shadows are strong, that I cannot help thinking there are also many more volcanos in the moon than have yet been discovered by a celebrated modern astronomer*. Those remarkable valleys, or cavities, discernible on her disk, have many of them a single hill in their centre, and are surrounded by a circular ridge of a similar appearance.

Query. May not the moon be surrounded by an atmosphere of pure air, which differing essentially in its properties from the atmosphere of our earth, might account for some of the phenomena of her appearance to us? An atmosphere of this sort might be so transparent as not to refract the rays of light in a sensible degree, or to produce the least change in the appearance of a star passing through it when an occultation

* Herschell,

is observed. At the same time, it would increase in a high degree, the inflammability and combustion of matter, so as to produce volcanos; and if we suppose the moon to have neither seas nor vegetation on her surface, the sun's light would be more strongly reflected than from the earth, where the rays are liable to absorption by water and vegetables.

XXIX.

Extract from a Diary of a Journey over the Great De~ sart, from Aleppo to Bussora, in April 1782. Communicated by Sir WILLIAM DUNKIN, and published with a View to direct the Attention of future Travellers to the Ruins described in it.

APRIL 16.

ET off at five in the morning; encamped at five in the evening; the day intensely hot; the soil in general sandy; some few shrubs and bushes, but now quite brown, and so dry, that with the least touch they fall to powder; many stalks of lavender and rosemary; and in very dry red sand several scarlet tulips; other sorts new to me, one of a singular kind, in colour and smell like a yellow lupin, but in figure like the cone of a fir-tree, from ten to twelve inches long.

After about two hours in this sort of country, the ground appeared more verdant and firm; we then came to some very extraordinary ruins our Shaikh had seen, but never had approached them before; we prevailed on him; he called the place Castrohuoin; another Arab called it Calmay; our Armenians, who interpreted for us in very bad Italian, called it Castroduo fratilli (I try to give the names from their mode of pronouncing); what we first saw was a square, each side about 400 yards long. The walls forty feet high, yet entire in many places; at each angle there is a circular tower, two others in each of the sides; they rise much higher than the walls; the towers and the walls constructed with very large blocks of cut stone. To what use the hollow of the square had

The

been applied, I could form no conjecture: in it are immense blocks of cut stone, and segments of arches of different dimensions, tumbled together in monstrous heaps. Near to the gateway by which we entered, two arches remain perfect, a third nearly so; they were probably carried all along the inside of (but distinct at least twenty feet from) the wall. These arches spring from very slender pillars, each pillar a single shaft; the arches are nearly semicircular, of the same beautiful white stones as the pillars. About a quarter of a mile from this square there is another, which appears to be a fourth part less; the entrance into this is under the loftiest as well as the widest arch of stone I ever saw: I had no means of measuring, which I much regretted : I cannot draw, which I regretted much more. proportions of the pillars, and of the arch which they support, conveyed to me something more just and beautiful than I can describe. The inside of the arch is richly ornamented with sculpture; at the sides there are niches, I suppose, for statues; the outer face of the building is composed of great blocks of stone as the greater square; and in many places yet entire, appear to be as well chisseled and jointed as the best constructed marble building I ever saw, even at Venice. The height of the wall seems to be equal to that of the greatest square; the thickness, which from some breaches quite through may be observed, from seven to eight feet, all through of the same stone, with little, if any, cement: the number and disposition of the towers the same as in the other; but in this, where the towers rise above the wall, they are more ornamented; two circles or bands of sculpture at equal distances appear relieved from the body of each tower: but as all the tops are broken off, I could not guess how they had been closed. sculpture on the inside of the great arch of entrance, and on many of the fragments of prostrated pillars,

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