from observations made at Munich, Stuttgard, Augsburg, and Vienna, extending through an interval of twenty-eight years. In addition to affecting the terrestrial atmosphere, it has been from time immemorial an almost universal opinion, that lunar influence operates upon organic life, and is unpropitious to it. The Roman poet speaks of "the moon's doubtful and malignant light: "

"incertam Lunam sub luce maligna."

Throughout the East the opinion is common, that the moonbeams are deleterious, injuring the sight, and defacing the countenances of persons who sleep exposed to them. The light of the moon, Plutarch supposed in his day to be an active agent in putrefying animal substances; and the fishermen of Sicily now cover the fish at night exposed on the sea-shore to dry, alleging that the moonbeams would otherwise putrefy them. It is supposed, also, that tender plants are often cut off in April and May by the moonlight. The facts observed in these cases are no doubt true, but referable to another cause than the one stated. Animal substances putrefy, plants are cut off, and sight is injured, by open-air exposure on a moonlight night, yet not because of that light, but of the removal of the clouds, the fine clear sky, which favours the radiation of heat, by which exposed bodies become colder than the surrounding air, and hence the mischiefs narrated. We cannot attribute to the moonlight any potential effect upon terrestrial substances, when it has been ascertained that chloride of silver, the colour of which suffers the greatest and most rapid change by an exposure to light, is not at all affected by the lunar beams condensed in the focus of a powerful burning-glass. Besides these supposed instances of lunar action, cases of disease, such as epilepsy and insanity, were believed to be largely influenced by the moon by the two great physicians of antiquity-Hippocrates and Galen; and many of the moderns have countenanced the same opinion. Hence the word lunacy is applied to mental distempers. There would be a reasonable basis for the idea in question, if it could be proved that the moon has any deranging effect upon the constituents of the atmosphere. But this remains to be shewn; and to suppose disorders of the brain to be exasperated by lunar changes, as an effect of those changes, may be safely dismissed as a vulgar conceit. Even were it incontestably established that such effects occur at such intervals, a simple coincidence would be proved, and the question of connection left untouched. There is some reason to suppose that exasperations of insanity are coincident with the full moon, owing to the more distinct lights and shadows of the night powerfully affecting the imagination.

With reference to one province of the satellite, that of giving light to the earth, there can be no difference of opinion as to its utility, inferior as is the borrowed lunar to the direct solar illumination. Owing to the unfailing prosecution of her orbital route from west to east about 13° daily, the moon rises at a mean rate 50 minutes later every day. This is the general rule. But there is a remarkable deviation from it in our latitude, when the moon's path lies in Pisces and Aries. This part of the ecliptic makes but a small angle with the horizon of those places that have considerable latitude, and, taking that of our own country as an example, as much of Pisces and Aries rises in two hours as the moon requires six days to travel through. The consequence is, that she differs but two hours in the time of her rising for six days together, or rises each day about 20 minutes later than the one preceding. This takes place in our autumnal months, September and October; and hence we have the harvest and the hunter's moon. It is true that the phenomenon of the moon's rising for a week together so nearly at the same period must occur every time she is in Pisces and Aries, or once a month. But she only rises as a full moon, with so little variation, about the autumnal equinox; and it is her appearance that arrests attention and renders the event remarkable. The husbandman prizes it as an important benefaction, lengthening out the day during

sea.

the appointed weeks of harvest, and affording useful aid in gathering in the fruits of the earth. The comparative proportion which the light of the moon bears to that of the sun is a problem to the solution of which the attention of several philosophers has been directed. The whole heavens covered with full moons would scarcely make daylight. From various experiments that have been made, it is supposed that the lunar light is only equal to the 800,000th part that of the sun; and, until very recently, its rays were believed to be without heat, as when collected by the aid of the most powerful glasses, no appreciable effect was produced upon the thermometer. But by concentrating them in a lens of three feet diameter, Melloni, the Italian philosopher, is said to have obtained a sensible elevation of temperature; and the same result has been gained by experimenting at a high altitude. In 1856, under the auspices of the British Association, Professor Smyth conveyed a large collection of instruments for scientific purposes to the Peak of Teneriffe, and made observations at two stations, respectively 8840 and 10,700 feet above the At both stations, the heat radiated from the moon, so often sought for in vain in a lower region, was distinctly perceptible. But, vastly inferior as is the lunar to the solar light, its utility has been appreciated in all ages and countries by both rude and cultivated nations. To those, indeed, who are the least advanced in civilisation, or who are locally situated apart from its aids, its value is the greatest. Owing to the rapid progress of the useful arts among the cultivated races, they have been abundantly supplied with the means of artificial light; superseding to some extent their dependence upon the arrangements of Nature, and lowering their estimate of the advantage of her provisions. To the inhabitants of London or Paris, whose streets are splendidly illuminated at night, the presence of the moon is more a matter of ornament than of use. But it is otherwise when the day has closed with the mariner at sea; the peasant homeward tracking his way through the drifted snow; the traveller in a strange country; and the barbarous migratory hordes of men. To such, when the day has departed, the moon pursues her nightly circuit through the heavens in beauty and brightness, as a friend in need, chasing away the gloom, revealing the features of the scenery, and disclosing the right path. To the Lunarians, if such there be, a similar service will be rendered by the earth, which, to those who occupy the presented hemisphere of the moon, will relieve with reflected light their fifteen days of darkness. The terrestrial world will exhibit to the lunar inhabitants all the phases which their dwelling presents to us, but upon a far grander scale, the earth appearing upwards of three times the size of the sun, and thirteen times greater than does the satellite, to ourselves. Its aspect will be perpetually changing by the rapid rotation upon its axis - its tracts of sea and continent being alternately presented; and provided with instrumental aid as powerful as that which we possess, a lunar dweller may discern various terrestrial phenomena the mighty masses of cloud that are pendent in our atmosphere, the flashing lightning, the fields of ice at the poles, and the occasional outburst of volcanic fires.

XTERIOR to our terrestrial world in the system, its noblest compeers are to be found, whether we consider the magnitude of their forms, the peculiarities of their structure, or the number of their attendants. The planets technically called superior are known to lie out in space beyond the orbit of the earth. This is shown by several decisive proofs. They never appear crescent-shaped like Mercury and Venus, or exhibit any perceptible phase when viewed through a telescope, but are always seen with a full orb, with the exception of Mars, whose appearance is often gibbous. Jupiter, Saturn, and Uranus always appear round, and the gibbosity of Mars is but a slight deviation from a circle. The inference is, that we see these planets in nearly the same direction in which the sun's rays enlighten them, and consequently the position of the earth must be comparatively proximate to the centre of their orbits. They are also never observed, when in the direction of the sun, to transit his disk, which would occasionally occur, if their path was interior to that of the earth, and carried them between us and the luminary. They are likewise seen at all distances from the sun, even in opposition, or in that quarter of the heavens which is diametrically opposite to the sun's place, rising in the east at sunset in the west, and being visible at midnight, which would plainly be impossible if the earth's orbit circumscribed theirs. These facts prove their position in the system to be exterior to our own. The external planets are chiefly distinguished from the internal by the attendance of secondary bodies, supplying in some degree to their primaries the place of the sun in his absence, and compensating for that diminution of his light when present, which arises from their vast distance from him. Mercury and Venus appear to have no moon, for, in connection with the earth, they answer the purpose of satellites to each other, Venus shining with great splendour in the night of Mercury, and our own globe forming a brilliant object in the night of Venus. At that point of the system in which we are placed, the scheme of satellites seems to commence, and with the exception of Mars and the asteroids it is a feature belonging to the other planets. If a moon should ever be discovered revolving around Mars, the law of secondary bodies attending the outlying planets would be unbroken from the point we occupy in the system to its outskirts, for the case of the asteroids may be excluded, their whole character being anomalous. Even as it is, the rule is general exterior to the earth's path; and there may be peculiar circumstances, not yet known, to explain the exceptive case of Mars. The number of secondary bodies appears to be proportioned to the wants of the primaries. While our globe has one, Jupiter, at five times the distance from the sun, has four; Saturn, at nearly ten times the distance, has eight, besides the enormous rings, which afford an illumination equal to several thousand such attendants; and Uranus, of nearly twice the distance of Saturn, besides his discovered five or six, may have hundreds that escape our notice, owing to the immense interval that separates him from us.

MARS, the nearest to us of the exterior planets, was, in former ages of superstition, the dread of the terrestrials on account of his fiery aspect, and ministered more than any other celestial object to give employment to the astrologers, and to fill their coffers:

"But most is Mars amisse of all the rest;
And next to him old Saturne."

harm

If Spenser were alive now, he must admit his words to involve a libel upon a very less body, fit to be commended to the inhabitants of the earth as an example of peacefulness and order, rather than regarded as a patron of belligerent propensities, delighting in "manslaughter and byrnyngs of houses, and in warres," as an old almanac states. The planet is placed in the system at a mean distance from the sun of 142 millions of miles, which is nearly fifty millions of miles farther than the earth. The space, however, between us and Mars varies prodigiously. When the two bodies are on the same side of the sun, they are five times nearer to each other than when on opposite sides, for then their distance is augmented by the entire diameter of the terrestrial orbit, or 190 millions of miles. On this account, the apparent size of the Earth will vary greatly as seen from Mars, while Mars varies in appearance to us from a diameter of 18" to 4". He thus dwindles from a considerable orb in the heavens to an insignificant speck, presenting a faint hazy appearance when most remote from us, and contending with Jupiter for the palm of splendour under a favourable juncture of circumstances. An era of this kind occurred in the month of August 1719, when Mars was not only nearest us, but within 2° of his perihelion; that is, the two events were almost coincident, of being nearest the earth and nearest the sun, and then his appearance was so brilliant as to fill the minds of the vulgar with alarm, being mistaken for a new luminosity in the skies.

The planet has been closely watched by many accurate observers, and his elements are known with considerable precision. Mars accomplishes his revolution round the sun in 6864 231, the length of his year, extending to nearly two of ours, travelling at the rate of 54 thousand miles an hour. In traversing the zodiac, he appears to move at the rate of about half a degree each day, passing through a whole sign in somewhat less than sixty days. Hence, if we know what constellation Mars has just entered, we may conclude that two months afterwards he will be in the next, and four months afterwards in the next, and six months after the date in the succeeding one. His period of rotation upon his axis is 24h 39m 21s, but a slight difference in excess from the length of the terrestrial day. His true diameter is computed to be 4100 miles, rather more than one-half that of our globe, and his volume is about one-fifth. His form is spheroidal, the diameter at the equator being one-sixteenth more than at the poles. From his period of rotation being so nearly equal to that of the earth, while his diameter is very little more than one-half, it might have been concluded that the inferior velocity of his equatorial regions would have produced a much less bulging out there than at the equator of the earth. But while the equatorial diameter of our globe exceeds the polar by twenty-six miles, that of Mars does so by two hundred and fifty, which gives a greater degree of oblateness to his form, and is probably due to his far inferior density. If the orbital career of the planet were suspended, his mass would plunge to the sun in 121 days 10 hours. To Mars, the solar diameter will appear one-third less than to us, and the solar light and heat be proportionably diminished; but his night-sky will be adorned by our globe and its satellite, a beautiful pair of objects, about a quarter of a degree distant from each other.

The physical constitution of Mars is in many respects analogous to that of the earth. Indeed, the agreement between them is greater than between any two bodies in the system, as far as our knowledge extends. An atmosphere surrounds the planet. His ruddy complexion, observed in very ancient times, has been attributed to its density, and regarded as a phenomenon similar to the redness of our morning and evening sky near the horizon, which arises from the sun's rays passing through the densest part of our atmosphere, which reflects or absorbs the other colours; while the red rays are those which

chiefly make their way through the resisting medium. The idea of Sir John Herschel is however more probable, that the fiery aspect of Mars proceeds from the geology of the

planet, its general soil having this colour, like the red-sandstone districts of the earth, but in a more decided manner. When viewed through a telescope, the surface exhibits a variety of spots, of which, as observed by Cassini, Hook, and Maraldi, we have several drawings. Some of the spots are changing and evanescent, and appear to be clouds and vapours floating in the atmosphere; but others are permanent, and are evidently geographical features of the planet-continents, seas, and regions of polar snow. The annexed view of Mars was taken by Sir John Herschel at Slough, August 16th, 1830, in the twenty-feet reflector. The darker parts are seas, which appeared of a greenish hue. The zone observable at the polar point is brilliantly white, but of variable brightness, and is conceived to be snow, its luminosity being least after exposure to the sun through the summer season of the planet, and greatest after the darkness of its long wintry night. There are thus points of striking accordance between the Martial and Terrene worlds.

Their periods of light and darkness, night and day, are nearly equal. Both have a succession of seasons, arising from the obliquity of their respective ecliptics, though of different duration. Both have an atmosphere clouds, rain, snow, continents and seas; but without an attendant moon, the oceans of Mars must be nearly tideless, only gently undulating like the waters of the Mediterranean and the Baltic. Each planet has also vast fields of ice and snow at its poles. Should the inhabitants of Mars take a view of our world through any far-seeing instrument like that with which we inspect their dwelling, the terrestrial aspect, viewed from that distance, in one of its phases will not be very remote from the sketch now given. Proceeding farther on an outward-bound course through the system, we arrive at the cluster of diminutive bodies, whose existence is a modern discovery. They present a variety of anomalies which distinguish them from the older planets; and received from Herschel the distinctive appellation of Asteroids, a Greek compound signifying the appearance of stars, but by others they are more properly called Planetoids, or small planets. Of these bodies, now (August 1858) fifty-three in number, four were discovered early in the century, Ceres, Pallas, Juno, and Vesta, as the result of a search conducted upon the presumption that some unknown orb lurked in the vast space between Mars and Jupiter. The first three are exclusively telescopic objects, and require the best instruments to be caught. But Vesta shines with a very intense light, as a brilliant point in the heavens, and has been observed on a clear evening by the naked eye. Following the order of succession in the system, Vesta is at the mean distance of 225 millions of miles from the sun, Juno 254, Ceres and Pallas 263. Their periods of revolution range from somewhat more than 3 to 4 years. The orbit of Juno is remarkable for its eccentricity, being so elliptical that the greatest distance of this minute world from the sun is nearly double the least. Both Ceres and Pallas appear to be surrounded with a nebulous haze.