It is perhaps too much to infer from these casual observations so wide a deduction as that all the travertine is due to this origin from sulphur waters charged with bicarbonate of lime; but it is not going further than is allowed by a prudent philosophy, to say that travertine is now forming on the shores of Lake Solfaterra from this cause.

3. Present Condition of Vesuvius.

The eruption of Vesuvius in February 1850, and that of the year previous, entirely changed the summit features of this ancient mountain of fire. The former crater disappeared, being filled with scoria and ashes, while two craters now оссиру the summit of the cone. The deepest and most active of these is that of February 1850, which is situate on the side of the cone nearest to Pompeii. It is somewhat lower,

and has a much greater depth than its immediate neighbour, which is on the side of the bay of Naples. We had no means of measuring its depth accurately, but judging from the time required for the returning sound of a stone cast into its mouth, as well as from inspection and comparison, we assumed the depth of the new crater to be from 800 to 1000 feet. It is acutely funnel-shaped at an angle of not less than 60°. It is impossible, because of the stream and vapour of sulphurous acid, to see its bottom, even if not prevented by the danger of the descent to a position where one might hope to catch a glimpse of its bottom. Its activity at present is confined to the emission of vapour, and even this seems at times, when viewed from the sea, to be wanting. On the summit, however, these vapours appear dense enough, and are sufficient to prevent the possibility of making the entire circuit of the crater. From this cause we were unable to examine the lip dividing the crater of 1850 from its neighbour. The observer is much struck, not only with the change of form in the summit, as shewn by the drawings of Professor Scacchi, but also with the sharpness of the lip of both craters, which is such that it is hardly possible for more than two persons to stand abreast upon it. During the late eruption, the lava found vent from the base of the cone on a level with the sand plain which fills the ancient crater of

Somma.

It here poured out a torrent of scoriaceous red lava through a well-defined canal. This is now entirely cold, and we collected from its sides abundant specimens of aphthitalite, which frosted over the rugged cavern like snow. Near this spot also are two fumeroles formed during the last eruption; the largest about 25 feet high, with an aperture of near ten feet, its outer walls black, rugged, and forbidding. The flow of lava from the eruption of 1849 was in the direction of the ancient Pompeii, and it was copious enough to destroy a small village with its vineyards, at the distance of several miles. The king of Naples has since erected a new village for the unfortunate inhabitants near the site of the former one.

During the past six years the king of Naples has also constructed a carriage road up the side of Vesuvius as far as the Hermitage, where he has a Royal Meteorological Observatory, under the direction of the celebrated Melloni. This road follows in a very serpentine path over and around the hill of ashes, which all who have seen Vesuvius will remember as forming a remarkable feature in its topography. In this manner, sections have been opened in the hill for a distance of three or four miles, and were these viewed without reference to the immediate proximity of the volcano which has produced the deposit, it would be easy to refer the whole to an alluvial origin, so characteristic are the undulating lines of deposition, the alternation of coarse and fine materials interstratified, including now large angular masses of rock, and again graduating into the finest silt and mud. In some places the lines of deposition are curved in regular undulations, and in others they meet at a sharp unconformable angle. Close observation alone detects that the whole material is volcanic-pumice, scoria, sand, and fine dust, including large blocks of inflated lava and tufa.

It is impossible to see any difference in the general character of these deposits and of those which cover Pompeii, only that the latter being mostly the result of one eruption are less varied than the former, and more regularly stratified. In both, the evidence of the aqueous action is very obvious; and we have historical as well as geological evidence of the VOL. LII. NO. CIII.-JANUARY 1852.

K

eruption of vast volumes of aqueous vapour with the lapilli,
scoria, and fine ashes from Vesuvius, which, condensing into
rain, produced a deluge of hot mud, filling the most intricate
recesses of the Pompeian houses, and producing the appear-
ance of an aqueous deposit in the ash hills of the flanks of
Vesuvius. In Herculaneum we see the same phenomena in
Here, owing to a much longer
a more remarkable manner.
accumulation of material-to subsequent overflows of lava,
and the superincumbent weight thus produced, with the aid
of water, the ashes were consolidated into so compact a mass
that some writers have even doubted whether Herculaneum
had not been destroyed by an overflow of lava in the first in-
stance. That such was not the fact is well known, and the
condition of the antiquities imbedded there quite forbid the
idea, were no other evidence attainable.

4. Meteorological Observatory of Mount Vesuvius.

The Meteorological Observatory recently erected at Mount Vesuvius, was projected by Professor Melloni, so well known to all the world by his memorable researches on heat, and the most distinguished of all the Italian physicists. The King of Naples gave the enterprise his sanction, and furnished the means to construct the building. The house is of ample dimensions, standing on an artificial terrace at the summit of the hill of ashes, which forms the limit of the arable region of Vesuvius, and at an elevation of about 2000 feet. The centre has three floors above the basement, and the two wings, each one floor above the basement; in the rear, and joining the main building, is a round tower, and the roofs are conveniently arranged for meteorological purposes. All the plans were furnished by Professor Melloni, who also superintended its erection, which, by an inscription on the exterior, appears to have been begun in 1841.

Unfortunately for science, the revolution of 1848 entirely arrested the farther progress of the undertaking; the house stands vacant, no instruments are provided, and, worst of all, Professor Melloni has been removed, not only from his direction in the Observatory, but also from his Professorship in the University, under the caprice of a despot who knows no law

1

but his own will, and who has shewn in this act that he was unworthy of so noble a subject.

5. Fish of Mont Bolca.

At Padua we found the most complete collection of the fossil fish of Mont Bolca, probably in the world; over 500 specimens, generally presenting both sides, some of them five or six feet long, and all remarkably perfect. We visited this celebrated locality last Friday. It is in a very wild and romantic region, surrounded by lofty mountains. Mont Bolca itself is 2000 feet high; and to the north and east the Tyrolese Alps rise abruptly, leaving a profound and steep valley between them and the base of Bolca. Columnar basalt in regular forms crowns the summit, and intrudes between the vertical fish-beds.

6. Mineralogical Notes.

Sacacchite is a silicate of lime and alumina, containing fluorine, and occurs in square prisms highly modified.

Leucite occurs at Vesuvius in the older ejected blocks, as well as the most recent lavas, and it is observed in some instances undergoing a change to Ryacolite, while still retaining the external form of leucite, and sometimes cavities of ryacolite crystals are formed in the leucite.

Zircon occurs at Vesuvius in beautiful white and blue octahedrons in the old ryacolite gangue. Fluor spar occurs in octahedrons with hornblende in the older lavas.

Forsterite is identical with anorthite.

Davyne is regarded by Professor Sacacchi as a variety of Nepheline. The six-sided prisms are striated longitudinally, and are modified by a plane on the terminal edges, and another on the lateral; it occurs in a compact pyroxenite gangue, while the nepheline occurs in a gangue of ryacolite.

Arragonite is formed in an old mine at Monte Vasa from day to day, at a temperature below that of boiling water. Buratite comes from Campiglia in the Maremma Pisena in Tuscany, and not from Volterra.

Tourmalines of Elba. In the Grand Duke's collection at Florence there is a specimen 11 inches square, with four erect green tourmalines and one prostrate, 2, 4, and 24 inches long, and to 1 inch thick. They are associated with orthoclase and crystallized quartz. The pink tourmalines of Elba have always the basal plane OR, while the green prisms are terminated with rhombohedral planes.

Analcime? A singular analcime-like mineral occurs at Monte Catini, in which the soda replaces the magnesia, according to Professor Moneghini of Florence, who obtained for its composition

[This result give the oxygen ratio for the protoxids, peroxids, silica, and water 1: 2: 6: 1}.]

Observations on the Zodiacal Light; with an Inquiry into its Nature and Constitution, and its Relations to the Solar System. By DENISON OLMSTED, Professor of Natural Philosophy and Astronomy in Yale College.* With a Plate. Read before the American Association for the Advancement of Science, at the Annual Meeting at Albany, August 1851.

I submit to the Association a series of observations on the Zodiacal Light, made by me at Yale College from 1833 to 1839, upon the basis of which I propose to offer a new description of this mysterious phenomenon, and a brief inquiry into its nature and constitution, and its relation to the solar system. Particularly, I propose to inquire whether or not it is the origin of the meteoric showers of November and August. Various circumstances conspire to interrupt the continuity

* In next number of this Journal a particular account of the Zodiacal Light as seen in Southern Africa will be given.