The above minerals have been described mineralogically in my previous report. It only remains to state the results obtained in the analysis of the chladnite. They are the following:

It consists, therefore, of 11 atoms tersilicate of magnesia +} of an atom of tersilicate of soda.

In operating upon the mixed powder of the stone, lime, alumina, and phosphoric acid were detected, ingredients which are supposed to have reference to anorthite and apatite.

APPENDIX.

I place the two stones now to be mentioned in an appendix, because the evidence of their extra-terrestrial origin is not, in all respects, perfect. While there is much in the circumstances under which they were found to countenance their genuineness, there still remain several obvious defects in the testimony upon which this depends; nor is this deficiency fully counterbalanced by the nature of the stones themselves.

a. Waterville, Maine.

For my first knowledge of this stone, I am indebted to Prof. Loomis, of Waterville college, Me., who incidentally mentioned to me, (during the meeting of the Association of American Geologists in May, 1845, at New Haven,) that Prof. Keely, of Waterville, had in his possession a portion of a stone that had fallen in that place. The latter gentleman has favored me with a specimen of the stone, and several communications relative to its discovery. He observes that its finder was Capt. Josiah Crosby, of Waterville, that he is a good observer of natural phenomena, has paid considerable attention to mineralogy, and that his character is beyond question. His statement is as follows:

"On a clear, star-light night in Sept., 1826, about midnight, a luminous fireball or meteor came from a southeasterly direction, apparently one-third or half as large as the moon, and proceeded with great velocity, (with a kind of rushing noise like the ap

proach of a high wind,) in a curved line and with a regular motion towards the earth. The light was intense and the tail or train was of a conical form, like the blaze of a lighted candle. It disappeared from my view, a moment before I heard a report, like that of a small cannon. A few days after, about one-third of a mile distant from the place where I witnessed the appearance described, I found, as I suppose, a fragment of this meteor." Several inquiries were, at my request, proposed to Capt. C., to which he replied in the following note, addressed to Prof. K. : "There has never been a glass-house in this section of the state. The nearest iron works are sixteen miles distant. Common brown earthen ware was manufactured formerly at a place onethird of a mile distant from the spot in a straight line. I have traversed the land a great number of times, bearing the circumstance in mind, yet I have never seen the like substance before or since. It was a solitary stone, the soil consisting entirely of a sandy loam. There was no stone wall, or accumulation of stones 'within two miles. The specimen, when picked up, appeared to be a newly detached mass. The grass upon which it lay was short and close to the ground, and was entirely unchanged in appearance."

Capt. Crosby presented the mass (whose weight appears not to have exceeded three ounces) to Virgil D. Parris, Esq., formerly a member of Congress, and now United States Marshal at PortMr. Parris gave Prof. Keely the fragment which was presented to me for examination, and subsequently has presented to him the remainder of the mass. Such is the history of this

stone.

Its appearance is that of an imperfectly stratified or laminated pumice stone, with double the ordinary compactness of this substance, the layers being one-sixth of an inch in thickness. It has very little tendency however to separate at these joints; and their existence even is chiefly denoted by a difference of color. The body of the stone is a light ash-grey, while at and near the joints it is iron-black. Indeed the powder of the black matter is attracted by the magnet. The outside of the stone has evidently undergone fusion, subsequently to the interior; and is coated by a thin red-brown crust. It is too vesicular in its texture to allow of a satisfactory determination of its specific gravity. The stone is composed of the following ingredients:

b. Concord, New Hampshire.

For a description of this stone see Vol. iv, ii ser., p. 353. In his account of this body, Prof. Silliman has made an inference in favor of its meteoric character, founded upon the supposed identity of its composition with the Bishopsville stone, or rather with the chladnite, which forms 90 per cent. of this stone. So far as the elements are concerned in the two bodies, the analogy is striking; but the analysis of chladnite, (not then published,) on which I asserted that it was a tersilicate, was based on Dr. Thomson's view of the constitution of silicic acid, whereas Prof. Silliman has adopted the atomic weight of Berzelius. The results of analysis, however, placed side by side, stand thus :

In addition to the analogy of elements found in the composition of these substances, it remains to be stated that there is a manifest resemblance between the melted surface of the Concord stone and certain parts of that of the Bishopsville meteorite, in color, lustre, translucency, and hardness, as well as in behavior before the blowpipe.

The extra-terrestrial origin of meteoric stones and iron-masses, seems likely to be more and more called in question, with the advance of knowledge respecting such substances, and as additions continue to be made to the connected sciences; I may therefore take an early occasion to present the Association with some views, founded in part upon Biot's theory of the aurora borealis, which seem to favor such an origin of meteorites.

The recent study of those frequently occurring and wide spread atmospheric accumulations of meteoric dust, (a single case being recorded where the area must have been thousands of square miles in extent, and where the quantity of earthy matter precip itated must have been from 50 to 100,000 tons in weight,) makes known to us the vast scale on which terrestrial matter is often pervading the regions of the upper atmosphere; and prepares us to appreciate the mode in which the peculiar constituents of meteorites may be translated to those remote distances, where according to the theory of Biot, the clouds of metallic dust are retained.

Great electrical excitation is known to accompany volcanic eruptions, which may reasonably be supposed to occasion some chemical changes in the volcanic ashes ejected; these being wafted by the ascensional force of the eruption into the regions of the magneto-polar influence, may there undergo a species of

magnetic analysis. The most highly magnetic elements, (iron, nickel, cobalt, chromium, &c.,) or compounds in which these predominate, would thereby be separated, and become suspended in the form of metallic dust, forming those columnar clouds so often illuminated in auroral displays, and whose position conforms to the direction of the dipping needle. While certain of the diamagnetic elements, (or combinations of them,) on the other hand, may under the control of the same force be collected into different masses, taking up a position at right angles to the former, (which Faraday has shown to be the fact in respect to such bodies,) and thus produce those more or less regular arches, transverse to the magnetic meridian, that are often recognized in the phenomena of the aurora borealis.

Any great disturbance of the forces maintaining these clouds of meteor-dust, like that produced by a magnetic storm, might lead to the precipitation of portions of the matter thus suspended. If the disturbance was confined to the magnetic dust, iron-masses would fall; if to the diamagnetic dust, a non-ferruginous stone; if it should extend to both classes simultaneously, a blending of the two characters would ensue in the precipitate, and a rain of ordinary meteoric stones would take place.

As favoring this view, we are struck with the rounded, hailstone-like form of many of the particles of composition (even though consisting of widely different substances) in nearly all stones, and even in many of the iron-masses. Nor are these shapes to be referred to fusion; they evidently depend upon a cause, analogous to that which determines the same configuration in hailstones themselves.

The occasional raining of meteorites might therefore be as much expected, as the ordinary deposition of moisture from the atmosphere. The former would originate in a mechanical elevation of volcanic ashes and in matter swept into the air by tornadoes, the latter from simple evaporation. In the one case, the matter is upheld by magneto-electric force; in the other, by the law of diffusion which regulates the blending of vapors and gases, and by temperature. A precipitation of metallic and earthy matter would happen on any reduction of the magnetic tension; one of rain, hail or snow, on a fall of temperature. The materials of both originate in our earth. In the one instance they are elevated but to a short distance from its surface, while in the other, they appear to penetrate beyond its farthest limits, and possibly to enter the inter-planetary space; in both cases, however, they are destined, through the operation of invariable laws, to return to their original repository.

SECOND SERIES, Vol. VI, No. 18, Nov., 1848.

54

SCIENTIFIC INTELLIGENCE.

I. CHEMISTRY AND PHYSICS.

1. On Nocturnal Radiation, &c.; by M. MELLONI, (Ann. de Chim. et de Phys., Feb., 1848.)-Previous experiments have determined the amount of radiation by thermometers at different distances from the ground, the lower thermometer being surrounded by the radiating substance. The lower strata of air being cooler than those above, reduce the temperature of the lower thermometer-while the naked instrument having itself a high radiating power, does not correctly indicate the temperature of the air in which it is placed.

To avoid these sources of error, the instruments should be placed at the same level, and that intended to measure the temperature of the air should have its radiation reduced to a minimum. As metal foil cannot be applied neatly to the bulbs, the author devised the following mode of experimenting.

A sound bottle cork is pierced with a hole to admit the stem of a thermometer, which is pushed through until the bulb is within of an inch of the cork. It must then be fastened with a little wax and with wedges of wood. The scale which should be marked upon the tube is taken off on a piece of paper and transferred to a thin slip of ivory. This is then fastened in a slit in the cork so that it shall coincide with the scale on the tube, and secured in its place. The end of the column of mercury and the corresponding degree on the scale can be easily seen at night, by holding a light behind the strip of ivory.

A little vessel of silver or brass, resembling a thimble, and with a polished surface, is next to be made; it must be large enough to hold the bulb of the thermometer, and to fit tightly on the end of the cork. A similar cap of thin tin plate is to be provided for the scale and tube.

The instrument thus prepared, was proved by experiment to be almost free from the influence of radiation, and consequently a true measure of the temperature of the air-on the other hand a coating of lampblack raised the radiation to a maximum. In the use of these thermometers, they were placed horizontally in tin vessels, having the form of a truncated cone two inches in diameter below, and seven inches above, about four inches deep, and supported on three feet formed by thin tubes of sheet tin two feet long. A hole at the side with a short tube to embrace the cork, allowed the introduction of the thermometer, its bulb being in the centre of the dish, and at little distance from the bottom; plates of tin served as covers.

We have been thus particular in describing these instruments, as they are decidedly the most suitable for this kind of investigation, which have ever been described.

Two thermometers furnished with polished caps, and a third with one coated with lampblack, were exposed in the tin vessels. While covered, they stood at the same height, but when the covers were removed from one of the two with polished caps and from the third, the latter (covered with lampblack) immediately fell, and in ten minutes