From the earliest times, there are to be found in authors, notices of the singular geological phenomena of floating islands. Pliny tells us of the floating islands of the Lago de Bassanello, near Rome; in Loch Lomond, in Scotland, there is or was a floating island; and in the Lake of Derwent Water, in Cumberland, such islands appear and disappear at indefinite periods. Mr. A. Pettingal, jun. has recently described a floating island, about a mile southwards of Newbury port, 140 poles in length, and 120 in breadth. It is covered with trees; and in summer, when dry weather is long continued, it descends to the bottom of the lake.--_American, Journal of Science_. _An immense Medusa_. A species of sea-serpent, was thrown on shore near Bombay, in 1819. It was about 40 feet long, and must have weighed many tons. A violent gale of wind threw it high above the reach of ordinary tides; in which situation it took nine months to rot; during which process travellers were obliged to change the direction of the road for nearly a quarter of a mile, to avoid the offensive effluvia. It rotted so completely, that not a vestige of bone remained.--(_C. Telfair, Esq. to R. Barclay, Esq. of Bury Hill._) _Himalaya Mountains_. Captain Gerard, in exploring these mountains, with a view to measurement, had ascended to the height of 19,600 feet, being 400 feet higher than Humboldt had ascended on the Andes. The latter part of Captain Gerard's ascent, for about two miles, was on an inclined plane of 42°, a nearer approach to the perpendicular than Humboldt conceived it possible to climb for any distance together.--_Heber's India_. _Hippopotamus_.