LAKES. 319 



may, it is certain there are several rarities in and near Rome, which we not only have 

 never seen, but have never so much as heard of ; and yet, if they had been the produc- 

 tion of Greece, or Egypt, or Asia, or any other country which we admire as fruitful in 

 wonders, they would, long since, have been the subjects both of our reading, conversa- 

 tion, and inspection. For myself, at least, I confess I have lately been entertained with 

 a sight of one of these our indigenous singularities, to which I was an entire stranger 

 before. My wife's grandfather desired I would look upon his estate near Ameria. As I 

 was walking over his grounds, I was shown a lake that lies below them, called Vadimon, 

 which I was informed had several very extraordinary qualities attending it. This raised 

 my curiosity to take a nearer view. Its form is exactly circular ; there is not the least 

 obliquity or winding ; but all is regular and even, as if it had been hollowed and cut out 

 by the hand of art. The water is of a clear sky-blue, though with somewhat of a green- 

 ish cast ; it seems, by its taste and smell, impregnated with sulphur, and is deemed of 

 great efficacy in all fractures of the limbs, which it is supposed to consolidate. Notwith- 

 standing it is but of a moderate extent, yet the winds have a great effect upon it, fre- 

 quently throwing it into violent commotions. No vessels are suffered to sail here, as its 

 waters are held sacred, but several floating islands swim about in it, covered with reeds 

 and rushes, together with other plants, which the neighbouring marsh and the borders of 

 the lake produce. These islands differ in their size and shape ; but the edges of all of 

 them are worn away by their frequent collision against the shore and each other. They 

 have all of them the same height and motion, and their respective roots, which are formed 

 like the keel of a boat, may be seen hanging down in the water, on whichever side you 

 stand. Sometimes they move in a cluster, and seem to form one entire little continent ; 

 sometimes they are dispersed into different quarters by the winds ; at other times, when 

 it is calm, they float up and down separately. You may frequently see one of the larger 

 islands sailing along with a lesser joined to it, like a ship with its long-boat; or, perhaps, 

 seeming to strive which shall out-swim the other : then again they all assemble in one 

 station, and afterwards joining themselves to the shore, sometimes on one side and some- 

 times on the other, cause the lake to appear considerably less, till at last uniting in the 

 centre, they restore it to its usual size. The sheep which graze upon the borders of this 

 lake frequently go upon these islands to feed, without perceiving that they have left the 

 shore, till they are alarmed by finding themselves surrounded with water ; and in the 

 same manner, when the wind drives them back again, they return, without being sensible 

 that they are landed. This lake empties itself into a river, which after running a little 

 way sinks underground ; and if any thing is thrown in, brings it up again where the 

 stream emerges. I have given you this account, because I imagined it would not be less 

 new nor less agreeable to you than it was to me ; as I know you take the same pleasure 

 as myself in contemplating the works of nature." 



There are various examples of these floating islands. Those of the lake Gerdau in 

 Prussia are said to afford sufficient pasturage for a hundred head of cattle, which have 

 actually been found grazing on them, and noble elms grow upon one in the lake Kolk, in 

 Osnabriick. These islands have been formed by the gradual agglomeration of vegetable 

 matter, reeds from the marshes and roots of trees, upon which the waters have deposited 

 fine sand and gravel held in suspension, and have obviously required ages for their 

 growth. The great raft near the mouth of the Mississippi is a production of an analo- 

 gous kind. This is composed of the wood annually drifted down that river and its tribu- 

 taries, consisting of the magnificent trees growing upon their banks, which fall into the 

 waters, owing to the floods undermining their foundations and loosening their roots. Ar- 

 rested by some obstruction in the river, a mass of timber has thus accumulated, and become 

 consolidated by the interlacing of weeds and the deposition of alluvium, so as to form what 



