Digits eclipsed 7° 23' on Sun's South Limb. This eclipse will not be total in any part of the United States, but proba bly will be so, in the island of Cuba. This is the fourth return of the total eclipse of June 16th, 1806. Digits eclipsed at Sunrise 2° 46'; at Greatest Obscuration 5° 29′ on Sun's North Limb. This eclipse cannot be central in any place. At the time of this eclipse the Sun and Moon are very nearly at their least possible distance from the Earth. Digits eclipsed 8° 11' on Sun's North Limb. The Sun will probably be centrally eclipsed in the Canadas and Labrador. Digits eclipsed 11° 1' on Sun's South Limb. It is supposed that the only similar Catalogue now extant is the one computed for Paris, from the old lunar tables of Mayer, by M. Vaucel, at the request of Louis XV, and published in the fifth Vol. of the " Mémoires de Mathématique et de Physique. Paris, 1768." Vaucel's Catalogue commences with 1767, and ends with 1900. By this it appears, that the only eclipse nearly central at Paris, in all this term of years, is the annular eclipse of Oct. 9th, 1847, which is also the only one of the magnitude of eleven digits. But in Boston, between 1791 and 1900, seven of this magnitude take place, three of which are annular, one total, and two annular within the distance of eighty English miles. The following are the solar eclipses at Paris, according to M. Vaucel, in the remainder of the present century. 1866, Oct. 8, 3.58 1900, May 28, 66 7 53 1867, M'ch 6, 9 26 II. METEOROLOGICAL AND GEOLOGICAL INFORMATION. 1. NATURAL HISTORY OF THE WEATHER. [From the Companion to the British Almanac for 1830.] Are you weather-wise? is a question often anxiously asked, when all the appointments and arrangements for the out-door happiness of a large party have been made, and every desirable object anticipated or secured, except the certainty of fine weather, or even a continuation of it, if it already exist. The tone of the answers to this important query is in general expressive of hope of what it might, rather than of confidence as to what it will, be. The same desire of information and the same uncertainty prevail in the deliberations upon the more important and extensive operations of man, wherever the action of the atmospheric agents may assist or interfere; so that the cunning cheat, who could make a parade of abstruse learning sufficient to mystify the uninformed, has, for centuries, found the sale of predictions as to the state of the weather, an abundant source of profit. "Quackery," to use the recent language of M. Bory de St. Vincent, "has too long abused the public credulity upon this subject; for it must be acknowledged, that these phenomena are connected with a train of agencies, whose very existence we can never appreciate, and whose powers are beyond our means of calculation." Still, by the light which has been thrown upon the operations of this part of nature by the philosophers of our own times, we can safely take some steps towards an acquaintance with those atmospheric changes which directly or indirectly affect all vegetable and animal life, and more particularly with the order in which they succeed each other. Provided with this knowledge, we may often be able to anticipate them, and timely prepare either to avert or diminish their injurious influence, or take the greatest advantage of opportunities which may be propitious to the increase of the subsistence, wealth, and happiness of the community. In the attempt to form a correct notion of the causes which produce those incessant variations in the atmosphere, which are popularly called the weather, it will be necessary to consider, briefly, some of the properties and constituent parts of that wondrous envelope of our globe.* CONCISE VIEW OF THE PROPERTIES AND CONSTITUTION OF THE ATMOSPHERE. That the atmosphere is a fluid completely surrounding the whole earth needs no demonstration; how far its dimensions extend into space is a problem of far more difficult solution. Had it been a fluid of uniform density, the length of the mercurial column suspended in the barometer, would have demonstrated that its greatest elevation could not have exceeded five miles; but the air being very elastic, the higher portions of the mass which covers our globe, sustaining a diminished pressure, must swell upwards, and occupy a proportionably wider space. This property removes the boundary of the atmosphere to a much higher elevation; and from the consideration that the reflection of the Sun's rays, unless the sky be overcast, is constant, so that there is total darkness in no climate, even at midnight, it has been inferred, that the elevation of the atmosphere must, at least, be equal to 1638 miles. This very great extension of a rare expansive atmosphere appears conformable to the general phenomena. Near the equator it may stretch out even much further, and yet its elevation can never exceed a certain absolute limit. Though this extreme boundary may surpass all our ordinary conceptions, it yet scarcely exceeds the twentieth part of the distance of the Moon, which was held by the ancients to communicate with our atmosphere. Though we can sound the depths of this great aërial ocean but approximately, we are not so situated with regard to its weight. This property has been long demonstrated to exist, and even those differences of pressure upon the earth, its supporting surface, which must attend the fluctuations of a body of such attenuated fluidity perpetually agitated, can be measured and compared. To the properties of magnitude and weight must be added those of elasticity, expansibility, transparency, and insipidity. Air is also generally considered to be invisible, but it is certain that, like water, it is a colored fluid; it is naturally blue, as that of the latter is green, * It would be extremely difficult, in an article which involves so great a number of facts and opinions, to assign an individual authority to each of the following statements. It is, therefore, proper to mention, that the authors who have been principally consulted for this abridgment of a very extensive and complicated subject, are these : Daniell, J. F., Esq., F. R. S.-" Meteorological Essays and Observations." 2d edit. Leslie, Professor-Articles "Climate" and "Meteorology," in the Supplement to the Encyclopædia Britannica; and "On Heat and Moisture." Forster, Thos., Esq. --Article "Cloud," in Supplement to Ency. Brit. but both colors acquire intensity only from the depth of the transparent mass. This we perceive in air, on viewing distant objects, whose colors are always tinted by the deepening hues of the interjacent range of atmosphere. The remotest hills seem lost in a cerulean vesture. The blending of the atmospheric azure with the colors of the solar rays, produces those compound, and sometimes remarkable, tints with which the sky and clouds are emblazoned. The constitution of the rare medium in which we "live, and move, and have our being," has been unfolded by the brilliant discoveries of modern chemistry. Experiments have been made at distant points, repeated on the summits of the loftiest mountains, and applied to portions of air brought down by balloons from the altitude of five miles; and the result has been the conclusion, that the constitution of our atmosphere is the same in all places on the surface of the earth, and at every elevation that has yet been explored. It appears to consist of a combination of two distinct expansible gases, the interstices of which are penetrated by ever-varying propor tions of condensible elastic vapor. The gases are combined in different quantities, a single portion of oxygen being united to three parts by weight, or four parts by bulk, of nitrogen; there is also a very slight admixture of carbonic acid gas, amounting to perhaps a thousandth part of the whole. The particles of the condensible elastic vapor or steam are invisible, and insinuate themselves between the particles of air, and filter through them with as little union, but with a similar kind of retardation, as those of water ascend and diffuse themselves through a sponge. These distinct atmospheres of air and vapor thus mechanically mixed, have different relations to beat, and their states of equilibrium, when enveloping a sphere of unequal temperature, are incompatible with each other. The triple assemblage is constantly exposed to the action of heat, a principle scarcely known but by some of its properties, which, combining with all bodies, even the most dense, either enlarges their bulk, or, dissolving the tie which holds their atoms in a solid form, sets them loose in fluidity, or finally expands them into vapor, and removes the seat of their existence from the earth to the heavens. The quantity of heat absolutely present in any one place is extremely difficult to measure; but its fluctuations are perpetual, and often evident. And as every accession or diminution of temperature is accompanied by some change, and often more than one, in the integral parts of bodies, or in the relation of one body to others which may be contiguous, it follows that these changes are infinite in number and character, and that the agent which produces them may be considered the main-spring of all the grand movements in the atmosphere. The atmosphere, so compounded, may be considered a universal solvent, and though itself inodorous, it is the medium of all smells, and dissolving the different odorous effluvia, is charged with the emanations of all the various substances it sweeps. |