ON THE PRESENT CONDITION OF VESUVIUS. BY B. SILLIMAN, JUN. 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 occupy the summit of the cone. The deepest and most active of these is that of February 1850, which is situated 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 steam and vapours 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 shown by the drawings of Prof. 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 aqueous action is very obvious; and we have historical as well as geological evidence of the 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 appearance of an aqueous deposit in the ash hills of the flanks of Vesuvius. In Herculaneum we see the same phænomena in a more remarkable manner. Here, owing to a much larger 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 instance. 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.-Silliman's Journal, September 1851. ON THE SULPHUR DEPOSITS AT SWOSZOWICE AND RADOBOJ. Professor L. Zeuschner has given a description of the sulphur stratum of Swoszowice near Cracow. It is situated in the tertiary formation. Sulphur and gypsum lie in parallel beds in a deposit of marl of considerable thickness. The entire deposit is 243 feet thick, and contains five layers of sulphur at almost equal distances of twelve feet. The uppermost layer of sulphur consists of grains of sulphur about the size of hemp-seed, which are disseminated through the marl. Sometimes the grains are attached like bunches of grapes. The second layer of sulphur is separated from the first by a gray marl of from 12 to 30 feet in thickness. The layer itself consists of small nodules of compact sulphur, is thicker than the former, being from 2 to 9 feet, and presents parallel layers separated by marl. The sulphur contains scarcely any admixture of foreign substances. In some places groups of sulphur crystals occur mixed with small crystals of calcareous spar. Only these two upper layers are worked, while the three lower ones are only known by boring experiments. The sulphur layer at Radoboj in Croatia has been described by A. v. Morlot. It was discovered accidentally in 1811 by a peasant, and has been worked from that time. The sulphur lies in a slaty marl, which is situated between the miocene formation and the calcaire grossier, and itself belongs to the eocene formation. The latter adjoins the dolomite of the magnesian limestone, and has an inclination rather less than 45°. The sulphur bed consists of four layers. The uppermost layer, for the most part 8 to 10 inches thick, contains nodules of sulphur from the size of a nut to that of a man's head lying separately in marl slate, and is only now and then accompanied by gypsum. Then follows an argillaceous sandstone 10 to 12 inches thick, which contains a remarkable quantity of fossil remains, not only of plants, but especially of insects and fishes. Under it lies a second deposit of sulphur, 10 to 12 inches thick, in a dark bituminous marly slate from which the sulphur has to be separated by distillation. A clayey bituminous marly slate, 12 inches thick, forms the bottom stratum. The sulphur beds are covered by, and rest upon hard marly slates.-Arch. de Pharm. 2 R., vol. lxvi. pp. 315,316. METEOROLOGICAL OBSERVATORY OF MOUNT VESUVIUS. The Meteorological Observatory recently erected at Mount Vesuvius was projected by Prof. 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 Prof. 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 further progress of the undertaking; the house stands vacant, no instruments are provided, and worst of all, Prof 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 but his own will, and who has shown in this act that he was unworthy of so noble a subject.-Silliman's Journal, September 1851. EXPERIMENTS ON THE APPLICATION OF ELECTRO-MAGNETISM AS A MOTIVE FORCE. BY M. ARISTIDE DUMONT. The author announces in the following terms the consequences to be deduced from the experiments reported in his memoir : 1. The electro-magnetic force, although it cannot yet be compared to the force of steam in the production of great power, either as it regards the absolute amount of power produced, or the expense, may nevertheless in certain circumstances be usefully and practically applied. 2. While in the development of great power the electro-magnetic force is very far inferior to that of steam, it becomes equal and even superior to it in the production of small forces, which may be thus subdivided, varied, and introduced into trades and occupations using but small capitals, where the absolute amount of mechanical power is less exerted than the facility of producing it instantaneously and at will. 3. In this point of view the electro-magnetic force assists, as it were, the usefulness of steam, in place of uselessly competing with it. 4. Other things being proportional, electro-magnetic machines with direct alternating movement present a great superiority of the power developed over rotating machines; since in the first there are no components lost, and with the same expense a much more considerable power is obtained than with rotating machines. 5. In machines of direct movement, the influence of the currents of induction appears less considerable than in rotating machines. 6. Finally, in the calculation of the expense, it is proper to include deduction of the value of the sulphate of zinc produced, and to take into consideration, that, in apparatus of any considerable size, the same battery may be used at the same time for the production both of the power and light.-Comptes Rendus, August 25, 1851. METEOROLOGICAL OBSERVATIONS FOR DEC. 1851. Chiswick.-December 1. Frosty: fine: uniformly overcast at night. 2. Overcast: clear. 3. Hazy cloudy: frosty at night. 4. Frosty: fine. 5. Hazy: cloudy: overcast. 6. Densely overcast. 7. Fine: cloudy. 8. Cloudy: clear and very fine. 9. Foggy. 10. Cloudy. 11. Clear and fine. 12. Very dense fog. 13. Foggy: hazy throughout. 14. Foggy. 15. Hazy. 16. Foggy: overcast. 17, 18. Foggy. 19. Very fine. 20. Hazy and drizzly: densely overcast at night. 21. Rain: boisterous at night. 22. Rain: clear at night. 23. Clear and fine. 24. Hazy: fine. 25. Clear and fine: cloudy at night. 26. Fine: sharp frost. 27. Frosty: overcast : slight rain. 28. Fine: densely clouded: clear. 29. Slight haze. 30. Foggy. 31. Frosty and foggy: hazy. Mean temperature of the month Mean temperature of Dec. 1850 Mean temperature of Dec. for the last twenty-six years 38°.88 6. Cloudy. Boston.-Dec. 1. Fine. 2-4. Cloudy. 5. Cloudy rain A.M. 7-9. Fine. 10. Cloudy: rain P.M. 11, 12. Fine. 13. Foggy. 14-19. Cloudy. 20. Fine. 21. Rainy: rain A.M. and P.M. 22. Cloudy. 23. Fine. 24. Cloudy. 25, 26. Fine. 27. Cloudy. 28. Cloudy: rain P.M. 29, 30. Cloudy. 31. Fine. Sandwick Manse, Orkney.-Dec. 1. Cloudy: damp. 2. Damp. 3. Showers: damp. 4. Rain: showers. 5. Showers: drizzle. 6. Bright: drizzle. 7. Cloudy. 8. Damp: showers: clear. 9. Damp: drizzle. 10. Cloudy: rain. 11. Damp: drizzle. 12. Bright cloudy. 13. Drizzle: clear. 14. Fine. 15. Fine: damp. 16. Bright: fine: damp. 17. Damp: fine: damp. 18. Bright: fine: aurora. 19. Cloudy: fine: aurora. 20. Cloudy: drizzle. 21. Rain: clear: aurora. Frost: clear: aurora. 23. Bright: clear: aurora. 24. Frost: aurora. 25. Frost : cloudy. 26. Fine: clear: aurora. 27. Fine: cloudy. damp. 30. Drizzle: rain. 31. Drizzle: cloudy. 22. 28. Cloudy. 29. Cloudy: |