river; this cave being a fathom wide, and higher than a man. It is dangerous to enter into this cave, because the waters come so suddenly, that it is sometimes impossible to escape them.

When it rains moderately, the water spouts with great violence 2 or 3 fathoms perpendicularly out of the pits Koteu and Keslenza. It comes likewise forcibly out of the spring Tresenz, as likewise out of Velkioberch, bringing with it at this latter abundance of fish, and soine ducks. But when it rains very hard and long together especially with thunder, then the water breaks out with very great force, not only from all the aforesaid pits, holes, and caves, but likewise at several thousand other little holes, which are all over the bottom of the lake, and which, when the lake is dry, drink up the waters of the eight rivulets that run into it, spouting several fathoms high, from some perpendicularly, from others obliquely, making a very pleasant sight. And out of the pits Vodonos, Rescheto, and some others, having great holes at the bottom, there comes with the water a great quantity of fish. In case of great rains, the eight rivulets running into it are likewise much increased; so that, all things concurring, this lake in 24 hours time will, from quite dry, be full of water, and sometimes in 18 hours; though at other times it has been known to be 3 weeks in filling; but it is a constant observation, that thunder helps much to fill it speedily.

This lake, being thus by turns wet and dry, serves the inhabitants for many purposes. For first, while it is full of water it draws to it several sorts of wild geese and ducks and other water fowl, as herons, swans, &c. which may be shof, and are very good meat. Next, as soon as the lake is emptied, they pluck up the rushes and weeds, which make excellent litter for cattle. Twenty days after it is fully dry, they cut a great quantity of hay upon it. After the hay is off, they plough it and sow millet, which sometimes by the too sudden coming of the water is destroyed, but it generally comes to maturity. While the millet is on the ground, they catch a great number of quails. The millet being off, there is a good pasture for cattle. When the lake is dry, there is great variety of hunting; as there comes out of neighbouring woods and mountains plenty of hares, foxes, deer, swine, bears, &c. as soon as the water is gone. When it is full, one may fish in it. In winter time it will be so firmly frozen as to bear all sorts of carriages, which is a great con venience to the people to fetch their wood and other necessaries

Lastly at the time when the water goes away, it yields great abundance of fish, as beforesaid. And that which is most wonderful is, that all this comes to pass in the same place, and the same year, viz. if the lake be early dry, and it fiil not too soon; but it is to be noted, that the hay does not grow, nor is the millet sown all over the lake, but only in the more fertile places.

There are only three sorts of fish taken in this lake, which are very well tasted. They are the mustela fluviatilis or eel-pout, some of them weighing 2 or 3 lb.; tench, some of them weighing 6 or 7 lb.; and thirdly, pikes, in very great plenty, of 10, 20, 30, and some of 40lb. weight; in the bellies of these it is common to find whole ducks. Crabs are found no where but in the pits Kamine and Sueinskajamma.

The cause or rather modus of all these wonderful phenomena in the lake of Zirknitz, is probably as follows. There is under the bottom of the lake, another subterraneous one, with which it communicates by the several holes described; there are also some lakes under the mountain Javornik, whose surface is higher than that of the lake Zirknitz. This upper lake is perhaps fed by some of those many rivers, which in this country bury themselves under ground, and has a passage sufficient to carry the waters they bring unto it; but when it rains, especially in thunder showers, which are the most hasty, the water is precipitated with great violence down the steep valleys, in which are the channels of these rivulets; so that the water in this lake, being increased by the sudden coming in of the rains faster than it can empty, swells presently; and finding several holes or caverns in the mountain higher than its ordinary surface, it runs over by them, both into the subterraneous lake under that of Zirknitz, into which the water comes up by the several holes or pits in the bottom of it, as likewise by visible passages above ground.

That some of these passages bring fish, some ducks and fish, others only water, seems to depend on the position of the inward mouths of these subterraneous channels; for if they be so constituted as to draw off the water from the surface of the upper lake, on which the ducks swim, they must needs be drawn away by the stream into these caverns, and come out with the water; but if the channels open into the upper lake under the surface of the water, and from thence ascend obliquely for some space before they come to descend; then the water they carry is drawn from below the

surface, and consequently can bring with it no ducks, but only fish. Those pits which yield only water may well be supposed to be fed by passages too narrow to let the fish pass, though their multitude may make the quantity of water they emit to be very considerable.

The manner of the falling away of the water or emptying of the lake I thus explain: After a long drought, or want of rain, all the springs that feed the upper lake under Javornik are much diminished: so that wanting fresh supplies it ceases to run over by the several channels; hence the lake of Zirknitz, and that under it are fed only by the eight rivulets that always fall into them; and then the water draws off faster than it comes in, both by the channels of Mala and Velkakarlouza, as also by a concealed subterraneous passage out of the under lake, which latter alone is able to transmit more water than the said eight rivulets afford. Consequently the lake must sink, and that in a certain proportion of time, depending on the quantity of water to be evacuated, compared with the excess of that which runs out above what enters it, in the same time. Those pits that are higher are soonest dry, the lower latest, and so come to be emptied in the order above described. And when the lake is all dry, then the said rivulets soak by several very little holes in the bottom into the under lake, and all their water is carried away by the subterraneous passage.

The ducks so often mentioned, and which are cast out with the water, are generated in the lake under the mountain Javornik; when they first come out, they swim well, but are stark blind, and have no feathers on them, or but few, and therefore are easily caught; but in 14 days time they get feathers, and recover their sight yet sooner, and afterwards fly away in flocks. They are black, only white on the forehead; their bodies not large, resembling ordinary wild ducks, and are of a good taste, but too fat, having near as much fat as lean. I killed some of them as soon as they had been cast out at Sekadulze; and opening their bodies, I found in them much sand, and in some few small fishes, in others green stuff like grass or herbs; which was the more strange, because I never found any green thing growing in any of the subterraneous grottos or lakes in Carniola. Almost every year, at a hole in the mountain called Storseg, about half a German mile from the lake of Zirknitz, near the town of Laas, whenever there happen great floods of rain, this

sort of ducks is cast out in great abundance, by the water gushing out with much force.*

[Vavasor, Phil. Trans. 1687.]

SECTION V.

BUBBLING, TEPID, AND BOILING SPRINGS †.

1. Introductory Remarks.

HEAT, water and vapours of various kinds, exist in prodigious quantities beneath the surface of the earth; and frequently, as we have already seen in the phenomena of volcanoes and earthquakes, burst forth from enormous jaws or openings, and with tremendous destruction. It often happens, however, that the openings are small and porous, and that the heat or vapours that ascend through them only ascend in a state of union with water. And hence, that almost infinite variety in the characters of those fountains and lakes that are found to be combined with extraordinary materials. In some cases the elastic gasses or vapours ascend from specific levity alone, and destitute of all taste and odour; and we have met with springs that bubble without boiling, or betraying heat or any other foreign` property. At other times, they are strongly impregnated with heat; and are then either tepid or boiling, according to the proportion of extricated caloric they contain. And occasionally, whether hot or cold, they are intermixed with metallic, sulphurous, saline or other substances, and hence assume the name of mineral waters while if the substance thus dissolved be combustible, as naphtha, bitumen or turpentine, the fountain will often inflame and burn upon the application of a lighted torch.

Upon this subject many of the observations offered by Dr. Tancred Robinson in the Philosophical Transactions, are worthy of at

*There is another, but a less scientific account of the same lake given in the same journal, by Dr. Brown, Vol. IV. year 1669.-The reader will also meet with other instances of ebbing and flowing waters in the ensuing sections; and especially in section x, Introductory remarks; and section xi. Lake Jezero.

For other instances, the reader may turn to the two ensuing sections.

tention, and especially the following, which we copy from the abridged edition *.

"The water of the noted boiling fountain at Peroul, near Montpelier, is observed to heave and boil up very furiously in small bubbles; which manifestly proceed from a vapour breaking out of the earth, and rushing through the water, so as to throw it up with noise, and in many bubbles; for upou digging any where near the ditch, and pouring other water on the dry place newly dug, the same boiling is immediately observed. The like bubbling of water is also found round about Peroul on the sea shore, and in the Etang itself. In order to discover the cause of this odd phenomenon, Dr. Robinson took some of the sand and earth out of the fountain and ditch, putting it into vessels, and pouring some of the same water upon it, there did not appear the least commotion or alteration ; the surface of the water continuing very smooth, equal, aud quiet. On further search, he discovered in several dry places of the ground thereabouts, many small venti-ducts, passages, or clefts, where the steam issued forth; at the mouths of these pipes, placing some light bodies, as feathers, small thin pieces of straws, leaves, &c. they were soon removed away. This vapour, on the application of a lighted candle or torch, did not flame or catch fire in the least, as the fumes running through a boiling spring near Wigan in Lancashire do, as noted in the Philos. Trans. N° 26; so that here we have two different sorts of steams causing these boilings, yet neither of the fountains are medicinal, nor so much as warm: the like is related by Varenius, near Culm, and by Dr. Plott in England. There are other boiling waters, of a quite contrary temper, being actually hot to several degrees, so as to boil eggs and many other things, put into them; as those near the Solfatara not far from Naples; as also on the top of Mount Zebio in the Duke of Modena's territories, not far from his villa near Sassolo; and in the source of the Em peror's bath at Aix la Chapelle, in the duchy of Juliers. Varenius tells us, that in Japan there bursts out a boiling spring, so hot that no water can be heated so much by the strongest fire; that it retains its heat three times longer than common water; and that it does not flow continually, but for two hours each day; and then the force and violence of the vapours are so great, that they remove

* Vol. III. p. 136,