A considerable diversity of opinion occurs in the state ments of travellers to /Etna, respecting other subjects of perhaps trifling importance. Some represent the smoke as rising with difficulty to the edge of the crater, and then rolling down the sides of the mountain ; while others describe it ascending perpendicularly to a great height, and afterwards falling clown in the lorm of white flowers. *Without questioning the accuracy of the ob servers, these accounts may easily be reconciled, by re flecting, that the smoke at different times may possess different degrees of density, according to the nature of substances from which it is derived ; and that the air may vary considerably in its specific gravity, and thus be capa ble of supporting the smoke at different heights.
Nor have travellers differed less in describing the ef fects of the diminished pressure of the air on the summit of /Etna. Some have complained of great difficulty in respiration ; while others have declared, that, in this res pect, they felt no inconvenience whatever. That at cer tain heights the air becomes so much rarified as to pro duce difficulty in breathing, appears pretty obvious from the accurate observations made by Saussure, in his tra vels on the Alps ; but it appears equally obvious from the same evidence, that, on the highest point of .Etna, no such effects ought to be produced. \Ve must there fore reconcile the accounts, by ascribing the difference of statement to a difference in the strength and habit of body of the different travellers.
Authors disagree respecting another subject, where it is not so easy to explain the origin of the difference. Spallanzani observes, that /Etna has at all times been very deficient in springs, and that the peasants are often seen roaming over the hill in every direction, in search of water ; while others state, that /Etna abounds with fountains and rivers of great magnitude. Mr Brydone describes several intermittent springs, which flow during the day, and stop during the night. Others describe springs that emit a noxious vapour, salt springs, and some whose waters arc used for dyeing particular co lours. \Ve are also told, that on the north side of the snowy region, there are several lakes which never freeze. M. Houel, in patticular, relates, that streams of water are seen issuing from the mountain at all heights, and continue to flow even during the summer ; nay, so high does he rate the quantity of water found on the sides of /Etna, as to suppose that the whole, if collected together, would fill the channel of a river 36 feet broad, and six deep. lie even finds considerable difficulty in explain ing the source of so much water. He thinks, that the
clouds, and the melting of the snow, arc inadequate to the supply; and therefore ascribes this abundance of wa ter to the condensation of aqueous vapour, which lie sup poses to be continually rising from the crater ; water, ac cording to him, being an important agent in the produc tion of a volcano. \Ve must therefore conclude, that. Spallauzani's observations are either limited, or inaccu rate. Perhaps a particular theory, which he seems to have formed on this subject, may have misled him. I lav ing observed that there is a great scarcity of springs in the islands of Lipari, he hastily concludes, that all volca nic countries are subject to the same inconvenience ; and he explains it in this manner :—When rain descends on volcanic mountains, it either falls on tufas and scoria, or on compact and solid lava. In the first case, it sinks into the earth, and not meeting with any of those strata which retain it, is lost for ever; in the latter case, it runs clown the declivities, forming river torrents, and hastily disap pears.
We shall conclude this general view of the surface of /Etna, by noticing a few particulars respecting its animal and vegetable productions. Besides the trees of a larger size, which we have already described, /Etna produces a great variety of plants and flowers. According to Din dorus Siculus, this mountain was celebrated by the an cients for its odoriferous productions. (See Dior!. Sic. torn. i. p. 322.) Plutarch and Aristotle somewhere in form us, that the smell of plants was so strong en some parts of its surface, as to render it impossible to hunt in that neighbourhood. Little, however, is yet known res pecting the flora of /Etna. Mr Brydone enumerates the following plants, viz. the cinnamon, sarsaparilla, sassa fras, rhubarb, and patina Christi.
The animal productions of /Etna are now much dimin ished both in size and number. Its horses and cattle were once esteemed the best in Sicily ; but the former are greatly degenerated. The race of stags is thought to be extinct ; but several species of wild animals still re main, as the wild boar, the roebuck, and wild goat. Spal lanzani informs us, that in the upper extremity of the mid dle region, he met with the following birds : partridges, (tetrad rufus ;) a kite, (falco ?nilvus ;) jays, (corvus glan dularius ;) thrushes, (turcius viscivorzt8 ;) several ravens and crows, and some birds of the titmouse kind ; but in the higher region he saw no other animals than some lion ants, (myrmelion formicarum,) which made their pit-falls in the dust of the lavas.