single point, which has its place unchanged among the stars during the whole continuance of the shower. In November, the radiant point rises above the horizon at midnight, in the Lion; in August it belongs to the circumpolar stars, in AR 50°, N. Decl". 51°, and were the relative velocities of the particles through the earth's atmosphere exactly determined, the eliptical dimensions of the cosmical zones about the sun might be readily calculated, and their periodic time concluded. A similar stream, with a radiant in corona, is noticed in the mornings of April 21st; and the 2nd of January, the 29th of July, 19th of October,. and 7th of December, have been named by Messrs. Quetelet and Julius Schmidt as prolific in shooting-stars. The different features of shooting-stars, like those of fireballs, are not numerous, nor do they appear to militate against the theory of their small-planetary or asteroidal character. Since the great fall of stones at Sienna, in Italy, in 1794, followed by others at Wold-cottage, Salés, and Benares, and at length by that of Aigle, no doubt remained of the facts which required scientific explanation; and copious collections of examples are now found in the largest mineralogical museums. Our own national collection contains 111 specimens of stones, and 79 masses of iron, known or reputed to have fallen from the air; and differs in this respect by only 18 to 25 localities from the large original collection of these minerals at Vienna. The falls of aerolites are attended by luminous phenomena in no way distinguishable from the class of larger fireballs. Although accounts are not so precise as to justify the conclusion of their identity, a review of numerous observations since the great fall of Sienna raises a strong presumption that the light of silent and detonationg fireballs is caused by the flight of small aerolites with high velocity towards the earth. Table of Aerolitic Falls attended by Fireballs since 1794. 1812. April 15, 4 p.m. 1820. July 12, fell; burst and deto- Large fireball; disappear- Erxleben, Saxony. Large fireball; seen at A stone fell with 5.30 p.m. 1821. June 15, doc. seen. Fine shooting-star, seen at Fireball of extraordinary tions like three can- a stone with loud concussions. 220 lbs. 5 ft. deep. Small stones fell after a loud report. 2 lbs., &c. Cold when they fell. Three stones fell after a noise like thunder. Very extensive shower of stones fell. 80 lbs., &c. Many stones fell, and broke in pieces. 10 lbs., &c. After an enduring report fell 2 iron masses, 1 miles asunder. 42 lbs. and 30 lbs. In 10 minutes an enduring report, and 2 stones fell. 2 lbs. and lb. Long after the thunder fell many stones. Stones fell. lb., &c. Oct. 1, by day. It appears from these accounts that fireballs scattering aerolites produce an audible concussion before the precipitation of the stones upon the ground. The volume of compressed air transported in front of a meteorite is perhaps sufficient by its liberation to convey an audible report from the almost empty spaces in which the concussions occur, but the obstruction of the denser air delays the catastrophe of the meteor's fall upon the earth until the thunderclap has already announced the blow of its arrival in the atmosphere. In the catalogue of 1400 meteors collected by Mr. Greg, 22 per cent. were attended by aerolitic falls. From various combinations of velocity and dimensions the disappearance of so large a proportion of fireballs may be explained by dissipation in the air; and of some, by loss upon the surface of the earth. Connected with this view of the origin of fireballs is the mineralogical examination of aerolites and aerosiderites. The stones of Stannern were in their external features studied by Von Schreibers, and Widmanstätten developed crystalline structure by etching polished surfaces of meteoric iron; Rose, Wöhler, and other chemists have analysed a large number both of aerolites and aerosiderites; and most recently Professor Maskelyne has been occupied in a minute study of their ingredients in thin sections of their substance, and by crystallographic measurements of some of their constituent minerals. It follows from the analyses, and from these microscopical investigations, that olivines, varieties of augite, eustatite, anorthite, and other as yet undetermined silicates, besides nickeliferous iron, metallic and pyritic, form the materials of the stones, and are mingled in crystals or spherules in a tufaceous but crystalline magma. Their structure, however, is not paralleled by any known geological rocks. Schreibersite, a singular phosphide of iron and nickel, is found in these stones, as elastic yellowish crystalline laminæ, and also appears, by its resistance to the action of acids, to assist in the production of the Widmanstättian figures seen in the nickel-iron alloy. It points to a scarcity of oxygen in the native region of the stones. Carbon and many metals, but no new element, are found among the mineral constituents. A hydrocarbon in the stones of Alais, Kaba, and Bokkeveld, but no certain proof of organic remains have been hitherto detected. The black enamellike glaze which envelops perfect stones is proof of sudden and momentary exposure to flame of intense heat, since the time when the meteorites were broken from their native rocks, and hurled upon the earth. The lunar "ballistic" theory of their origin is exposed to the objection of enormous volcanic activity necessary for a single accurate aim with aerolitic velocities, no doubt greatly exceeding those of circumterrestrial orbits. Such volcanic action is not perceived in the neighbourhood of the centre of the moon's visible disc. Their course is therefore more probably of a planetary nature and orbitual about the sun. The crepuscular atmosphere in which meteors are luminous, has been called by M. Quetelet the stable atmosphere, distinguished by dryness and immutability from the unstable atmosphere below, in which rain is prepared, and storms burst forth and commingle the parts. Positive electricity he conjectures to reside upon the lower, and negative electricity upon the upper portions of this lofty atmosphere, which by librations about the centre of its figure may cause the known magnetic disturbances and variations of the needle. At the base of this region M. Quetelet supposes the aurora to have its place; banks and arches of light being formed horizontally near its lowest confines and streamers from these shooting upwards, to relieve from time to time the varying tensions in the stratum. In this view, negative horizontal currents, following the sun, explain the southward drift of the auroral arch, and luminous discharges towards the upward pole of the dipping-needle occasion a canopy of converging beams arising from the arch. Dr. Plücker has indeed shown that in gases moderately dilated, luminous currents obey the rotatory influence of the magnet, but that in extremely rare gas the discharge is stationary and confined to the direction of the magnetic lines of force. The phenomena of luminous meteors and the aurora are thus allied to one another by their appearance at the outer confines of the air, and well directed observations of their particulars are a source of instruction at once to the astronomer and the meteorologist. But in our present uncertainty of the material, and of the physical and mechanical constitution of these extreme boundaries of air, projects of observation must aim at results very difficult to anticipate or to define, and the words of Benzenberg himself still ring in our ears, "Such a question will have time." [A. S. H.] ANNUAL MEETING, Friday, May 1, 1863. THE DUKE OF NORTHUMBERLAND, K.G. F.R.S. President, in the Chair. The Annual Report of the Committee of Visitors for the year 1862 was read and adopted. The amount of Contributions from Members and Subscribers in 1862 amounted to £3079. 13s.; the Receipts for Subscriptions to Lectures were £560. 14s.; the total Income for the year amounted to £4630. 8s. 1d. On Dec. 31, 1862, the Funded Property was £29,341. 2s. 2d. ; and the Balance at the Bankers, £804. 3s. 4d., with Six Exchequer Bills of £100 each. A List of Books Presented accompanies the Report, amounting in number to 161 volumes; making, with those Purchased by the Vol. IV. (No. 38.) H Managers and Patrous, a total of about 558 volumes (including Periodicals) added to the Library in the Year. Sixty-two Lectures and Twenty-one Evening Discourses were delivered during the year 1862. Thanks were voted to the President, Treasurer, and Secretary, to the Committees of Managers and Visitors, and to Professor Faraday and the other Professors, for their services to the Institution during the past year. The Special Thanks of the Members were voted to Sir Henry Holland, Bart. Sir Roderick I. Murchison, K.C.B. and Samuel Reynolds Solly, Esq, for their Donations for the purchase of Scientific Apparatus. The following Gentlemen were unanimously elected as Officers for the ensuing year :— PRESIDENT-The Duke of Northumberland, K.G. F.R.S. MANAGERS. Sir William George Armstrong, F.R.S. Sir George Everest, C.B. F.R.S. John Peter Gassiot, Esq. F.R.S. Sir Roderick I. Murchison, K.C.B. D.C.L. F.R.S. James Nasmyth, Esq. William Frederick Pollock, Esq. M.A. Robert P. Roupell, Esq. M.A. Q.C. Charles Wheatstone, Esq. D.C.L. F.R.S. Sir Henry Holland, Bart. M.D. D.C.L. Colonel Philip James Yorke, F.R.S. F.R.S. Hon. and Rev. Samuel Best. VISITORS. George J. Bosanquet, Esq. Captain Frederick Gaussen. The Earl of Rosse, F.R.S. Chancellor The Earl Stanhope, D.C.L. F.R.S. Pres. George Tomline, Esq. M.P. |