but which was too often employed to subserve the evil designs of the despotic emperors under whose sway the priestly orders were subdued. It would be out of place to record here, at length, the details of the system itself, or to trace the gradual process by which astrology--deriving its origin from pure and lofty conceptions of the divine power, wisdom, and goodness-fell to the position it has now so long occupied, and became the tool of cheats and charlatans. It may be mentioned, however, that the idea of physical influences exerted by the planets in their varying positions, has been entertained by many who fully recognised the absurdity of the so-called astrological systems. Bacon (who was, however, but superficially acquainted with astronomy, and strongly prejudiced against the Copernican system) considered an inquiry into such influences likely to lead to valuable results. 'Astrology,' he wrote, 'is so full of superstition, that scarce anything sound can be discovered in it; though we judge it should rather be purged than absolutely rejected.' He then propounded his 'Astrologia Sana,' which should contain inquiries into—(i.) the commixture of planetary rays in the different positions of the planets with respect to one another and on the zodiac ; (ii.) the zenith distances of the planets, or the planetary seasons; (iii.) the influences of the planets at their apogees and perigees; and (iv.) 'the other accidents of the planets' motions, their accelerations, retardations, courses, stations, retrogradations, distances from the sun, &c.; for all these things affect the rays of the planets, and cause them to act either weaker or stronger, or in a different manner.'* The following lines of Chaucer present the gloomy and dismal ideas which astrologers naturally associated with Saturn's dull light and sluggish motions: My dere doughter Venus, quod Saturne, Min is the strangel and hanging by the throte, The murmure, and the cherles rebelling, * Advancement of Learning,' Book iii. Chap. 4. I do vengeaunce, and pleine correction, The falling of the toures and of the walles I slew Sampson in shaking the piler. The derke tresons, and the castes olde: Another superstition, whose origin is equally obscure with that of astrology the idea, namely, that the planets exerted influences (each on its respective metal) over the labours of the alchemist—is mentioned by the same poet in the Chanones Yemannes tale. He thus succinctly states the distribution of the metals among the planets Sol gold is, and Luna silver we threpe; And Venus coper, by my faderkin.* * No satisfactory explanation has been given, so far as I know, of the distribution indicated above. That the two most valuable metals should be assigned to the sun and moon needs no explanation; the silvery light of the moon, and the yellow or red light of the sun whenever it can be viewed by the naked eye, make the distribution still more appropriate. On a different principle one can understand why quicksilver should be assigned to Mercury, which is so difficult to detect, and whose motions are so rapid. On other principles the association of Mars and iron may be explained: for some resemblance can be imagined between the colours of the ruddy planet and of the red oxide of iron, or Hæmatite; or the employment of iron in war might suggest the association; or, lastly, the invigorating and tonic properties ascribed to medicines containing iron correspond with the influences attributed to Mars by astrologers. The association of lead with Saturn may be explained on similar principles: the protoxide of lead (or Massicot) is of a pale yellow colour, somewhat resembling that of the planet; or one may imagine lead assumed as the representative of the dull, slow-moving Saturn, from some such fanciful association of ideas as that expressed by Armado in 'Love's Labour's Lost,'-' Is not lead a metal heavy, dull, and slow?'; or, lastly, the association might have been suggested by the chilling and deleterious effects peculiar to medicines containing lead-still called by doctors Saturnine medicines. Why tin and copper should be assigned respectively to Jupiter and Venus is not very obvious. The connection between the name of the latter metal and that of the island Cyprus sacred to Venus is noticeable. A singular coincidence may be mentioned here:-in the list of metals in Numbers, chapter xxxi, verse 22, we have the representatives of the sun, the moon, and the four planets probably known to the Jews at that time; and these four, 'the brass, the iron, the tin, and the lead,' are arranged in the order of the distances from the sun of the corresponding planets. That the word translated brass signifies copper is clear from the words of Job, chapter xxviii, verse 2, 'brass is molten out of the stone.' D Let us now turn from the false systems and idle fancies which throve with rankest luxuriance-like fungous growths in darkened nooks-amid the ignorance and superstition of priest-ridden ages, to the awakening of science at the dawn of a new era. The life of Nicolaus Koppernik, or Copernicus-the restorer if not the discoverer of the true system of the universe-belongs to the latter part of the fifteenth and the beginning of the sixteenth century; an age--as has been well remarked by Humboldt—' coinciding in a wonderful manner with the age of Columbus, Gama, Magellan; the age of great maritime enterprises; the awakening of a feeling of religious freedom; the development of nobler sentiments of art.’* During the first years of the sixteenth century Copernicus was engaged at Rome, at Padua, and at Bologna, in discussing with the astronomers of the day the various theories which had been invented to explain the planetary motions. Struck with the complexity of these theories he was led, after trying several hypotheses (probably including the system generally attributed to Tycho Brahe) to the conviction that the sun is the centre around which the planetary scheme revolves. We find in this arrangement,' he says, 'what can be discerned in no other scheme--an admirable symmetry of the universe, an harmonious disposition of the orbits. For who could assign to the lamp of this beautiful temple a better position than the centre, whence alone it can illuminate all parts at once? Here the sun, as from a kingly throne, sways the family of orbs that circle around him.'† The new system met with fierce opposition; not, at first, from the priesthood, but from astronomers. It was not merely that the views put forward were opposed to opinions that had been held so long this would in any case have been sufficient to rouse a strong feeling of opposition; but the system presented by Copernicus was wanting in simplicity. If he could have done away altogether with the old hypotheses of eccentrics and epicycles, the new system might have been more favourably received. This, however, he was unable to effect. His own observations bad shown him that the apparent planetary motions were too complex to be satisfac * 'Cosmos,' vol. ii. part 2, § vii. De Revolutionibus Orbium Coelestium,' lib. i, cap. 10. torily explained by any hypothesis of simple circular orbits. He therefore retained in a modified form parts of the cumbrous systems of his predecessors. Nearly three-quarters of a century after the publication of the celebrated work of Copernicus, Kepler, who had become in early youth an ardent convert to the new doctrines, was able to remove from the scheme of the universe the last traces of the Ptolemaic hypotheses. Tycho Brahe, strenuously opposed to the views of Copernicus, had erected an observatory at Uraniberg, where he had traced the paths of the planets on the celestial sphere with instruments more powerful and accurate than those employed by Copernicus. Kepler availed himself of a series of observations of the planet Mars made by Tycho Brahe with these instruments, and applied them to an investigation of the Copernican system. It was not his object to overthrow the doctrines of circular motions and uniform velocities, but to determine by what combination of eccentrics and epicycles the actual movements of the planets could be explained. Mars was in every respect the best selection he could have made. This planet is the nearest of the superior planets, and therefore its motions on the celestial sphere are swifter than those of Jupiter and Saturn; its orbit is also very eccentric; * on both accounts the true combination of epicyclic and eccentric motions should be more easily detected in the case of Mars than of any other planet. Kepler calculated the motions that would result from such combinations with wonderful patience and accuracy, compared them with the actual motions of the planet, and was compelled to reject successively nineteen different hypotheses. Having exhausted the combinations of circular and uniform motion, he began at length to inquire whether the orbit of Mars, obviously oval, might not be an ellipse; and whether his velocity, obviously variable, might not on the supposition of an elliptic orbit-be found to vary by some simple law. At this new problem he worked with unflagging energy and patience, trying and rejecting * Mars in aphelion is more than 152,500,000 miles, in perihelion little more than 126,500,000 miles from the sun; the difference of these distances is greater than onefourth of the earth's mean distance from the sun. See fig. 3, Plate VI. numerous hypotheses. Finally, his labours were rewarded by the discovery of the true laws of planetary motion, constituting the two first of the laws of Kepler.' They are these:— 1. Every planet moves in an elliptical orbit, in one focus of which the sun is situate. 2. The line drawn from the sun to a planet (or the radius-vector of the planet) sweeps over equal areas in equal times. From Saturn's motions in his orbit we can draw an illustration of these two laws. Let s, fig. 3, Plate VI., be the sun, E E′E"E" the orbit of the earth, s s's"s"" Saturn's orbit. These orbits are both ellipses, but in the figure they are represented by circles, because (on the scale of the figure) the difference of the axes of Saturn's ellipse would be very nearly, the difference of the axes of the earth's orbit altogether imperceptible even on measurement. The eccentricity of the earth's orbit is also too small to be noted in the figure;* the eccentricity of Saturn's orbit will be at once observed. At e the earth is in perihelion; E, E′, E′, and E’” are the positions of the earth at the winter solstice, at the vernal equinox, at the summer solstice, and at the autumnal equinox, respectively at 8 Saturn is in perihelion, at s" he is in aphelion, and s s" bears to ss a proportion rather greater than that of ten to nine. More exactly-the radius of the circle E E'E"E""' being taken as 1, the radius of the circle 8 N s'n' is 9.538850; ss" is 10.072533; and ss is 9.005167. The two orbits, as already stated, lie in different planes, the line of whose intersection passes through the sun: in our figure NS N' is this line, N being Saturn's ascending node; thus if the earth's orbit be supposed to lie in the plane of the paper, the part N 8'N' of Saturn's orbit lies above the paper, and the part N'8"N below. The lines kk' and ' indicate the distances from the plane of the ecliptic of the points s' and s""', at which Saturn attains his greatest departure from that plane. † It is hardly necessary to remark that the eccentricity may be very observable in an ellipse, even when the outline differs inappreciably from a circle: the difference of the semi-axes of such an ellipse bears a very small ratio to the distance of either focus from the centre-the ratio, namely, of the versed sine to the sine of a very small angle. For instance, the distance of the sun from the centre of Saturn's orbit is no less than 48,917,000 miles, while the difference of the semi-axes of Saturn's orbit is only 137,000 miles, or less than 17th part of the former difference. The orbits of the planets Mercury, Venus, Mars, and Jupiter, are respectively |