and of the astronomical articles in the supplement to the Encyclopædia Britannica, will notwithstanding be novel and acceptable to many.

From the theory of the reciprocal attractions of the three first satellites, La Place has discovered two very remarkable theorems concerning their motions. He found, that the mean motion of the first satellite, added to twice the mean motion of the third satellite, is rigourously equal to thrice the mean motion of the second satellite; that is making m the mean motion of the 1st, m' that of the 2d, and m" that of the 3rd, we have by the theorem,

m+2m'!=3m', or
m+2m"-3m'=0

By taking the mean motion of the satellites for 100 Julian years, as determined by De Lambre, La Place found, that

m+2m"-3m=only 9 seconds.

a coincidence between theory and observation, which is truly astonishing.

The second theorem deduced by La Place is equally curious, though from particular causes, it does not accord so well with observation. He found, that the epoch of the first satellite, minus three times that of the second, plus two times that of the third, is exactly equal to a semicircle, or 180 degrees, that is, making 777" the mean longitudes, or epochs of the satellites, we have

1-31+2=180, by theory.

By taking the real epochs of the three satellites for the midnight, beginning the 1st January, 1750, as determined by De Lambre, we obtain

-31'2" 180o 1/ 3.6.

This result differs only 63 seconds from the theory; but the cause of this difference is very satisfactorily explained by La Place.

From the last of these theorems it follows, that the three first satellites of Jupiter, can never be eclipsed at the same time. For if this were possible, the longitude of the three satellites would be equal at the time of their eclipse, that is /==", consequently,

which is impossible. When the 2nd and 3rd satellites are eclipsed at the same time, their longitudes will be equal, that is, l'—"; consequently in this case, the theorem becomes

-=180;

that is, the difference of the longitudes of the 1st and 2nd is 180°, but the 2nd being in opposition to Jupiter at the time of its eclipse, the 1st satel lite must be distant from it 180°; consequently, when the SECOND and THIRD satellites of Jupiter are simultaneously eclipsed, the FIRST is always in conjunction with Jupiter. On the contrary, it is obvious, that when the sun is simultaneously eclipsed by the SECOND and THIRD satellites, that is, when they pass at the same time across his disc, the FIRST satellite is in opposition to the planet.

By following out this principle, we shall find, that when the FIRST and THIRD satellites are simultaneously eclipsed, the difference between

either of their longitudes and that of the SECOND is 60°, for in this case Z", and the equation becomes

In like manner we shall find, that when the FIRST and SECOND are simultaneously eclipsed, the difference between either of their longitudes and that of the THIRD is 90°, or the THIRD is in quadrature with Jupiter. For in this case ll', and hence,

-21'+21=180°, and
-l + "= 900.

It is obvious from these interesting results, that a wonderful provision is made in the system of Jupiter, to secure to that planet the benefit of his satellites. When Jupiter is deprived at the same instant of the light of the 1st and 2nd satellites, or of the 1st and 3rd, the remaining one of the three first, cannot possibly be eclipsed at the same time, but is in such a point of its orbit, as to give considerable light to the planet. The simultaneous eclipse of the 2nd and 3rd satellites forms an exception to this remark, for at the same instant the 1st satellite has its dark side turned to the planet. Even in this case, however, the 1st satellite, when emerging from the sun's beams, is gradually turning more and more of its luminous hemisphere to Jupiter, to supply the loss of light arising from the want of the other two satellites. pp. 157-159.

The detail of Schroeter's and Herschell's observations on the moon, are, we think, given more at length, than was due to their importance; yet, we doubt'not, many will consult with much pleasure, the tables of the heights and length of base of several lunar mountains, as deduced by those celebrated astronomers. In the supplementary chapter on eclipses, we were pleased with the catalogue of solar eclipses visible at Paris during the 19th century; from which it appears that the only annular eclipse that will be seen there in the course of the century, will occur on the 9th of October 1847. From the tables of transits in chap. vii, it appears that the next transit of Mercury will happen Nov. 11th, 1815, and the next transit of Venus on Dec. 8th, 1874. For the circumstances of these and other subsequent transits, the reader may consult the work itself.

We are most dissatisfied with those chapters in Dr. Brewster's supplement, which are devoted to physical astronomy. He is not uniformly successful in developing the theories of others; and he is still less successful in speculating upon abstruse matters. The former arises principally, we apprehend, from an attempt to be familiar and popular where the subject will not admit of it: the latter, at least in the speculations respecting the comet of 1770, and the origin of the four new planets, from the circumstance that the hypothesis the doctor has started is utterly untenable.

We have no doubt that in much less than five years he will be very sorry that he should have suspended any part of his reputation upon such crude speculations as those to which we now advert. But we need not dwell upon these topics. Dr. Brewster is now engaged in a work (The Edinburgh Ency clopædia) more suited to, his talents and knowledge, and better calculated to extend his fame. We wish him success in the continuation of that work, and sincerely regret that his attention should have been diverted from it, by an undertaking, in our estimation, so unworthy of him, as framing an appendix to a mere horn-book for smatterers in astronomy. Art. IV. Descriptive Travels in the Southern and Eastern Parts of Spain and the Balearic Isles, in the year 1809. By Sir John Carr, K. C.

IT was time for our adventurer to proceed toward Seville. Some of the persons going the same road carried boughs of the palm-tree, which, when blessed by the priest, become infallible charms against thunder, lightning, and the devil'; on which account they are to be seen twisted round the grating of the balconies in numerous houses in Spain. He thus distinguishes the ranks of inns.

A fonda is the principal inn in a town, where the traveller may expect to find food (though most likely to be execrably bad) and wine provided. A posada is an inferior inn in a town, where lodging only is found, and if the traveller wishes to eat, he must either bring, or send out into the town and buy, what he wishes. A venta is a solitary house situated on the roads, in which it is seldom that any thing more than eggs and bad wine can be procured. p. 69.

At one place on the road he saw, for the first time, nine or ten horses moving in a circle and treading out the corn;' which he afterwards' found to be the common method of thrashing in Spain.' And he adds, on the authority of a curious ancient book, which we think it highly creditable to the literature of so gay a personage to have studied, even though so defectively as to fall into the little error of putting horses for oxen,that this was the practice of very early times: his words are, This method, we are informed by the scriptures, is coeval with the time of Moses.'-On the route to Seville our author saw vast tracts of uncultivated land, a denomination he probances to be applicable to two thirds of Spain. He deplores the ruin of agriculture by the expulsion of the Moors, condemns the policy of eating up the wicle country with sheep, and then exporting the wool raw, and celebrates a treatise on VOL. VII. 3 T

6

this and the connected subjects, by Don Gaspar Jovellanos. Arrived at Seville, he got with difficulty into the best inn, to which, he solemnly avers, the vilest hedge ale-house in England would have been infinitely preferable.' It is, however, very evident the house must have been intended originally for his betters, we should guess for Askapart or St. Christopher, at the least as he says, the 'looking_glasses are suspended about eleven feet from the ground.' He was accosted by two poor wretches in rags, who addressed each other as Senor and Cavallero, with "Live the English, but perish Napoleon." He surveyed the cathedrals, towers, and Moorish palaces; and was exceedingly fierce in mind against the 'besotted monks' of San Francisco, who keep eleven paintings of Murillo rotting in the cloisters, and will neither sell them nor put them in a situation less exposed to dampness and eventual destruction. At the very same time that the city was honoured by the presence of Sir John, it was disgraced by that of the mock-majesty called the Central or Supreme Junta (pronounced Hoouta)' the names of whose Dons component he here sets in pillory in two rows, just putting a label of exemption from mud on two or three. He got into excellent company, in which he heard the British Constitution highly lauded by an hidalgo, who gravely illustrated it to the auditory by a comparison with the Trinity. In England,' he says, such a comparison would have been deemed blasphemous; here, it was received as an ingenious mode of demonstration.'—As a man eminently conscientious, the knight was doubtless very much distressed by what he experienced here of an east-wind of highly immoral tendency. It affects,' he says, the moral as well as the animal system, and has a peculiar influence on the bad passions, to such a degree, that during its prevalence, the most abominable excesses are sometimes committed, particularly assassination.' p. 88. He says that the Spanish physicians are still decidedly of the school of Doctors Galen and Sangrado, as to the bleeding practice. He declaims in a spirited style against the gross and silly superstition, mixed too with levity, the female morals,-and the cowardly submission to the French, in this renowned city. Noticing a remarkable arrangement in the Spanish division of labour, he says,

A stranger will also not fail to be struck with the numerous escribedores or scriveners, who sit at their desks all day, in arched open recesses, on the basement floor of a street close to the cathedral. These functionaries are applied to, to draw up petty agreements, to adjust trifling accounts for the ignorant, and to write letters for those who cannot write themselves. They will also, 1 am informed, for a trifle, carry on a tender correspondence between

two unlettered lovers. There are a great number of these readywriters in Cadiz, and in all the principal towns of Spain.

Sir John experienced the greatest difficulty of breathing in the saeva mephitis' of the Supreme Junta, which he represents as also very noxiously affecting the animation, the courage, and the patriotism, of the people of Seville. In whatever way that people might be affected by the presence of such a body, it is easy to comprehend that an Englishman, from having been accustomed to contemplate a noble practical example of the opposite qualities, must abominate a government that could be foolish and depraved enough, according to the following description, to seek to maintain its consequence by a display of vain pomp, and by patronizing jobbers, contractors, place-hunters, and the basest corruption.

"The cloven foot' (of the Junta) was sufficiently visible under the imperial robe which the members had assumed.'-All was inflated and blustering loyalty within this city. The streets swarmed with officers and commissaries in gaudy regimentals and embroidered coats, waiting in servile attendance upon the Supreme Junta, to procure, by the basest means, commissions, jobs, and contracts. "Death to Napoleon," was the burthen of every song. A suspicious, rather than a patriotic vigilance, seemed to centinel every avenue of every street. A patriotic and popular general, was seized because he was observed to examine one of the gates rather minutely; and the fury of the mob, excited by a stupid and savage priest, was directed against a young English artist of merit, for pencilling the ass of a water-carrier in his sketch-book, and he was saved from destruction only by the intrepidity of his brother, who was attached to the British embassy.' p. 100.

All this savage heroism and patriotism sunk into a tame submission to the enemy, a few months after our knight's visit, and he cannot contain his anger to think of it. There is reason to doubt whether he recovered from the effects of the atmosphere of the Junta on his gay and good-natured soul, till he had inade a voyage of many hours down the Guadalquivir, and arrived at a delightful spot, a striking contrast to the streets and mob of a barbarous city.

After passing through fields of tomatas and melons, by the side of plumb, pomegranate, orange, and citron trees, we saw a mule who under the shade of silver poplars, and unattended, was raising water to the surface from a deep well, by turning a large wheel, to the circle of which earthern jars were attached, to supply the lemon and orange groves, which extended a great way before us, with the frequent moisture they require. From this primitive contrivance, we approached a group of female peasants, who were busily and variously employed under the shade of bowers of vines, running the length of the cottage front, from which they projected. Grapes hung from the roof in rich, luscious and ponderous clusters; below, pigs, goats, and poultry, in