20 APRIL 1889, Page 23

The Floating Island in Derwentwater. By G. J. Synions, F.R.S.

(E. Stanford.)—Very few probably of those who claim a close acquaintance with Derwentwater know of the existence of "the Floating Island." Nor is this to be wondered at when we re- member that numbers regarded it as a myth, and still look upon it as such. But it certainly is astonishing that a natural occur- rence of such rarity should have attracted so little notice, and have been dismissed with a few contemptuous remarks. Yet the history of the Wand, as narrated by Mr. Symons, is unique among natural phenomena. The island rose for the first recorded time in July, 1773 (it only rises during the summer months), and since then has appeared at irregular intervals till 1887, its last appear- ance, when, indeed, it rose twice, in honour, wo suppose, of the Jubilee ; though it appeared twice in 1815, curiously enough, we notice, in the same months as the later appearance. Such is its history. Mr. Symons begins his book by describing his own experi- ments on the island, and then gives a record of all the known appear- ances of the island with the dimensions attributed to it. After this we are introduced to instances related by various writers of floating islands, all of which resemble the Derwentwater one only in floating ; they never sink, and generally attach themselves to the banks. The theory held by the earliest investigators of the mystery scarcely deserves mention ; but its very absurdity shows they were at a loss to understand its existence. The only sensible theory, that its light density, assisted by the buoyancy of the marsh-gas, enables it to rise, ceases to be altogether satisfactory, as Mr. Symons hints, when we find that no other peat-bed behaves in a like manner. The island, or peat-bed, is entirely organic, and rests, when sunk, on diatomite. How the supply of gas is kept up, is to Mr. Symons a puzzle. The gas, however formed, together with the entirely organic nature of the island, is, doubtless, the chief cause of the phenomenon. Mr. Symons's sketch is most interesting, and we hope others will manifest a similar enthusiasm, tempered with respect, for one of Nature's most curious freaks.