The motions indicate a path not re-entering some at least of those which travel on into itself. These are of two orders: elliptic paths of great eccentricity are in those which retreat from the sun on a reality to be classified apart from the hypath tending with continual increase of perbolic comets, as having had a different distance to become more and more nearly origin and a different history. We might, parallel to the path by which they had indeed, reverse the argument just adapproached him; and those whose re-duced, and reason that the hyperbolic treating path carries them divergingly comets ought not to be classified apart away so that they retreat towards a dif- from the comets of long period, because ferent part of the heavens than that from perturbations excited within the solar which they arrived. Technically, the system might change an elongated elliptwo orders are those of comets pursuing tic orbit into a hyperbolic one. (i.) parabolic and (ii.) hyperbolic paths. point at issue is thus seen to resolve In reality, however, we may dismiss the itself into the question whether we can parabolic path as never actually followed assert that there are comets which from by any comet, any more than a truly cir- the earliest times (the youth of the solar cular path is ever actually followed by system) have belonged to it (i.) with short any planet. We may take it for granted periods and (ii.) with long periods, while that any comet which seems to follow a (iii.) other comets have visited it from parabolic path really follows either an other systems. We find in fact that the enormously elongated oval path, and so attempt to classify leads in this case, as belongs to our second class; or a path it has led in so many others (as perhaps carrying it forever away into outer space, it inevitably must lead, if properly conand nearly in the direction from which it ducted), to the question of origin. had arrived, but not exactly. A comet's And here perhaps the question will path could only have the true parabolic arise, may we not cut the Gordian knot form by a perfect marvel of coincidence; by denying that even the comets of short and in point of fact if a comet could by period can be separated from the hypersome amazing chance approach our sun bolic comets which visit our system from on such a path, the very least of the mul-interstellar space? I am aware that the titudinous disturbing attractions to which theory of comets and meteors which the comet would be exposed would suf-Schiaparelli has advanced, and which fice to change the path either to the ellip-many in this country have viewed with tic or the hyperbolic form. considerable favour, points to this conAnd here we may pause to inquire how clusion. For according to that theory far the second of the three classes into meteor-systems are groups of discrete which comets have thus been divided can bodies which have been drawn towards be regarded as a class apart. Does the our solar system, gradually lengthening mere fact that a comet has a re-entering out as the process of indraught continued, path so that, unless perturbations af- and have then been compelled by the fect it, the comet will travel in continual perturbations to which they have been dependence on our sun afford a suffi-subjected within our system, to become cient reason for distinguishing the comet members of it; and as comets and mefrom others which travel on a hyperbolic teor-systems have been found to be assopath? It appears to me that this ques-ciated together in some mysterious way, tion admits of being answered in two this theory of the introduction of meteorways. When we remember that a comet systems is in reality a theory of comets. approaching our system on a slightly Now since some certainly among the hyperbolic path might have that path meteor-systems have periods of moderate changed into an elliptic figure by the length, this theory of Schiaparelli's would perturbations to which the comet would regard the short-period comets as drawn be subjected during its visit, we may out of the interstellar depths, while manireasonably decide that the mere fact of a festly it would be absurd not to extend comet pursuing an elliptic path ought Schiaparelli's theory to hyperbolic comnot to be considered a valid reason for ets. In fact, we know that he himself distinguishing it from one of the hyper-regards his theory as requiring the occabolic comets. But when we consider, on the other hand, that there are comets like those of Jupiter's family, which are quite distinctly separated by the nature of their paths from the hyperbolic comets, we may not unreasonably infer that sional appearance of meteors of hyperbolic path, and therefore as not merely consistent with the phenomena of hyperbolic comets, but accounting for them. Adopting his theory, then, to its fullest extent, we should regard all comets and meteors as bodies coming from the inter- velocity at given distances from the sun. stellar depth: for it is not easy to see Thus, when at the distance of Neptune how any comet or meteor-system could its velocity would be 47 miles per secbe so far distinguished from its fellows ond; at the distance of Uranus, 5'9 as to be regarded as originally a member miles per second; of Saturn, 8.3 miles; of the solar system. of Jupiter, 113 miles; of the asteroids, But for reasons which appear to me from 15 to 16 miles per second; and the incontrovertible, I find it impossible to velocity in crossing the distances of give in my adhesion to Schiaparelli's Mars, the Earth, Venus, and Mercury, views, in the form in which he presented would be 208 miles, 259, 303, and 41'4 them. A line ought to be carefully miles per second respectively. Now we drawn between what has been proved know that the greatest velocity which any and what has not been proved respecting given planet can communicate to a body the opinions which Schiaparelli has ad- approaching it under its sole influence vanced. His most happy conception, from interstellar space is very much less that meteors would be found to travel in than the velocity which such planet can the paths of comets, has been realized, communicate to a body approaching it and no possible question can be raised as to the completeness of the demonstration; but it is quite otherwise with his supposition respecting the manner in which meteoric systems or comets have been introduced into the solar system. It not only has not been proved that comets have been compelled by the perturbations of the planets to become permanent members of the solar system, but under the sun's influence in addition to its own, for the communication of velocity to a moving body is a process requiring time, and in the latter of the two cases just considered the body is for a much smaller time under the influence of the planet. And the velocity which cause we only require to consider the ratio in what follows. Then we have grave doubts rest on the bare possibility 18 √JE of such an event occurring. = I I- = 25'9 2a } = 25'9, I 4a 32a2 0'000000000809375 smaller terms, Let it be remembered that the conditions of the problem are purely dynamical. We know that a comet's head obeys if a is made infinite. But if a be taken equal to half the laws of gravity, and whatever pecul- the distance of Alpha Centauri, say 100,000, we have iarites may affect the motions of the 25'90'00006475 matter of comets' tails are not by any means such as would help to render easier the captures conceived by Schiaparelli. Confining ourselves then to gravity, we can determine readily in what way a comet might be captured. Take the case of a particle travelling towards our solar system from out the interstellar depths under the influence of the sun's attraction. Such a particle may be regarded as practically approaching the sun from an infinite distance, and we know its all the terms after the first being together manifestly thousands of miles. It is a The comparison is easily made in any given case. Take, for instance, the planet Jupiter, supposing it at rest, and a particle drawn towards it from an infinite distance under the combined influence of the sun and planet (the particle lying originally on the side away from the sun). We readily obtain for the velocity V of the particle just as it is reaching the surface of Jupiter the equation a planet can communicate under any cir- shown to be impossible for Jupiter to cumstances represents the velocity which, withdraw much more velocity than he had under similar circumstances, the planet already communicated; and similar recan withdraw from a moving body. So marks apply, of course, to Saturn, Urathat Jupiter, Saturn, Uranus, and Nep-nus, and Neptune. tune, are severally unable to deprive The application of these considerations a particle which, drawn in by the sun's to Schiaparelli's theory is easily perattraction, passes near to them, of more ceived. In order that a particle attracted than a portion of the velocity which these from outer space may be compelled to planets are respectively able to commu- travel in a closed orbit around the sun, nicate to a body approaching them from its velocity must be diminished. And infinite space. Taking, for example, the this can very readily happen. But for the case of Jupiter, we may regard 40 miles particle to travel in an orbit of a particu per second as a sort of negative fund lar extent or mean distance, its velocity from which Jupiter would have the power where it crosses the distance of the disof drawing, to reduce the velocity of turbing planet must be diminished by a bodies moving from him, if Jupiter were certain amount; and in dealing with the sole attracting influence under which Schiaparelli's theory, it is a cardinal consuch bodies had acquired their velocity; sideration whether the observed orbits of but in the case of bodies which have been periodic comets are such that we can addrawn inwards by the sun's attraction, mit the possibility of their resulting from the fund is reduced, as shown in the note any diminution of velocity which the disbelow, to about 303 miles per second. turbing planet could have produced. Now this might seem ample when we Taking, for instance, the November meremember that the velocity of a body teors, which pass near the orbits of Uracrossing the path of Jupiter under the nus and the earth, and do not approach sun's influence alone would be but 113 any other orbit near enough for any such miles per second. But it is to be ob- effects upon the orbital motions of these served that the estimate only applies to bodies as we are now dealing with. bodies moving all but directly from Jupi- may dismiss the earth from consideration ter, and coming all but into contact with at once, because our planet is far too his surface. The power of Jupiter in small to modify the motions of bodies this respect diminishes rapidly with dis-rushing past her with the velocity, nearly tance from the surface. At a distance 26 miles per second, which the sun comfrom Jupiter's centre equal to four times municates to bodies approaching him his radius, his power is already dimin- from interstellar space, by the time they ished one half, and this distance is far reach the earth's distance from him. within that of even his nearest satellite. Uranus then alone remains. Now the Moreover, it is to be noticed that a body present velocity of the November metewhich moves in such sort that Jupiter ors when crossing the orbit of Uranus exerts his most powerful retardative in- amounts to about 1 1-2 miles per second. fluence, must have moved for some time The velocity of a particle approaching previously in such a way that Jupiter the sun from interstellar space would be exerted nearly his most powerful acceler-nearly six miles per second when at the ative influence.* It may be readily distance of Uranus. It may be seriously V = √(11'3)2 + (40)2 = less than 41'6; while 40; so that a body approaching the sun under his sole influence would have, at Jupiter's distance, a velocity of 113 miles per second; one approaching Jupiter under the combined influence of the sun and planet would reach Jupiter's surface with a velocity of 416 miles per second; and a body approaching Jupiter under his influence alone would reach his surface with a velocity of 40 miles per second. So that Jupiter helping the sun adds a velocity of 30°3 miles per second as compared with the velocity of 40 miles per second, which he can communicate to a body approaching him from infinity. It is manifest that a particle in approaching from without must be, in the first instance, accelerated by We questioned whether, under any circumstances whatever, a particle crossing the track of Uranus without encountering the planet could be deprived of 4 1-2 any planet to which it draws near, no matter what the Both Jupiter and Saturn can perturb the November meteors, and thus modify the shape and position of the meteoric orbits; but such changes, though by no means inappreciable, are utterly insignificant compared with those required to change the motion of a body approaching the sun from interstellar space into motion in an orbit like that of the November meteors. miles per second of its velocity. For suppose, on the other hand, that comets though Uranus can deprive a body di- have crossed the, interstellar spaces, comrectly receding from him (and starting ing to us from the domain of another from his surface) of a velocity of about 13 sun, is to remove the difficulty only one miles per second, yet the considerations step. We know that comets pass away above adduced show that only a fraction from the domain of our sun to visit some of this velocity could be abstracted from other sun after an interstellar journey of a body moving past Uranus; and it is tremendous duration; and to suppose certain that if so large a reduction as that comets, whether of hyperbolic or 4 1-2 miles per second could be effected elliptic orbit, came to us originally from at all, it would only be by a singularly the domain of another sun, is merely to close approach of the particle to the sur-suppose that that happened to such face of Uranus. But setting apart the improbability that a body arising from interstellar space could be in this way compelled to travel in the orbit of the November meteors, the possibility of such a capture would not prove the possibility of the capture of a flight of bodies large enough to form that meteor-system and its accompanying comet. If the whole material of the system and its comet had arrived in a compact body, the material attractions of the parts of that body would be sufficient to keep them together; whereas, in point of fact, the November meteor-system and its comet occupy at present a large range of space, even if the meteors be not scattered all round the orbit (however thinly along portions thereof). If, on the other hand, the material of the body were not in a compact form, the body would be necessarily large, and a portion of it only would be captured by Uranus. Nay, it is not even necessary that this should be conceded. For though we admitted that the whole of a large and tenuous body not kept together by the mutual attraction of its parts or by cohesion, might be captured, it is manifest that different parts would be captured in different ways, and would thenceforth travel on widely different orbits. That a system of bodies already drawn out into an extended column, and in respect of length already resembling the meteor-systems we are acquainted with, could be captured, as Schiaparelli's theory requires, and all sent along one and the same closed orbit, is altogether impossible. comets millions of years ago which we know to be happening to other comets at this present day, but not by any means to explain the nature of comets or their origin. We know that many comets leaving our system to visit others had not their origin within our system; and we cannot assume as possible or even probable that any comet had its origin within the domain of another sun than ours, unless we assume as possible or probable that some among the comets leaving our own sun had their origin within our sun's domain. cannot Thus, then, we have been led to the conclusion that whether we adopt, with Schiaparelli and others, the theory that comets with meteoric systems can be drawn into the solar domain, or regard such an event as of very infrequent occurrence, we will find that the origin of comets must be looked for within solar systems; or rather, since we claim to trace back comets any more than planets or suns, to their actual origin, we may say that at an early period of their existence comets belonged to the solar system. The system has had no more occasion, so to speak, to borrow comets from other systems - that is, from other suns-than these have had to borrow comets from it and from each other. We decide, then, that comets may certainly be classified into those which belong to our solar system from the earliest period of their history, those which visit it from without, and pass away to other suns, and an intermediate class consisting of those which having visited it from It is to be noticed also that we gain without have been constrained, by pernothing, as respects the interpretation of turbations affecting them within it, to comets, by adopting Schiaparelli's hy- become attached permanently to its dopothesis. To assume that cometic mat- main. We may note also that as there ter has been wandering about through are comets now belonging to our solar interstellar space, until the sun's attract- system which originally belonged to other ive influence drew such matter towards solar systems, so probably many comets the solar system, is to explain a difficulty originally belonging to our solar system away by advancing another still greater; are now either attending on other suns or moreover, we have not a particle of evi- wandering through the star-depths from dence in support of the supposition. To sun to sun. theme of a splendid addition to the "Histoire des Variations des Eglises Protestantes," if the pen could still be held by Bossuet; and for want of a Bossuet, bigotry may accept a Veuillot. But we think that the satire and the jubilation of Catholic controversialists will yet be found as baseless as were the predictions that the disruption of the Scottish Church would injure Presbyterianism. The rupture was really a sign that the days of indifference had passed away, and that Scotland had regained some of the grim earnestness with which the Covenanters had braved the dragoons of Claverhouse. Nay, the disruption has stirred both sections of the Scottish Church with a It has been from viewing the matter in | and now she is about to be cut asunder by this way, recognizing the almost decisive the discords of her own house. Such an evidence that comets have from earliest ending of such a history might be the times been members of our solar system, that I have been led to inquire into the possibility that some comets may have been expelled from the sun, and that others those, namely, which seem attached to the orbits of the giant planets may have been expelled from those planets when in their former sun-like condition. The evidence to show that there is an adequate expulsive power in the sun is striking, and we may reasonably infer that the small sums formerly dependent upon him had a similar power. The motions of the members of the comet-families of Jupiter, Saturn, Uranus, and Neptune, accord far better, too, with this theory than with Schiaparelli's. It is to be noticed, however, in conclu-zeal which, in the easy-going days of sion, that we may also not unreasonably admit the possibility that comets may be, as it were, the shreds and fragments left from the making of our solar system and of others, since the sun and planets in their former nebulous condition and ex-ing disruption of that Church which inpanded forms would have had a power of capturing these wandering shreds which at present they no longer possess. From The Spectator. THE PROTESTANT EVANGELICALS AND LIBERALS OF FRANCE. Hume, might seem to have vanished forever in favour of a gentlemanly paganism. Hence the disruption was really a blessing in the guise of a calamity. And such, we are convinced, will also be the com herits the organization, which is still charged with the spirit, and which is glorified by the fame of the Huguenots. It is true that there remains no such future for the Protestantism of France as there is for the Protestantism of Scotland. The French Reformed Church has abandoned all hope of ever becoming a dominant creed, and sometimes it has seemed to be almost dead. A revival of its energy would not touch the great inert mass of the French people, unless, indeed, it were to produce some teacher of immense genius; but the effect of the Huguenot creed has been so noble, that its new symptoms of life must be as welcome to the politician as they are to the theologian. IT may seem sad that, after three centuries of a glorious history, the Reformed Church of France should be on the eve of disruption. She withstood massacres, of which the slaughter of St. Bartholomew was only the chief; she remained uncrushed even after half a million of her members had been driven into exile by the most desolating persecution recorded The Revolution found the French in the history of France; she survived Protestants suffering from the same lasthe loss of perhaps another half-million, situde as all the other Christian Churches. who were sent to the galleys, killed, or Catholicism had sunk into a decorous converted to Catholicism by the sabres formality, the Protestantism of England of dragoons; she kept alive her Puritan and Scotland was in a like state, and perritual and creed in those churches of the haps the worst sign was that even bigdesert which have added imperishable otry had scarcely the nerve to persecute. chapters to the history of Christian hero- There is always hope of a zeal which is ism; she lived to see her oppressors faithful unto slaying. The descendants driven forth to become a byword and a of the Huguenots could still indeed musshaking of the head unto the nations; ter a strong body, but a long and terrible she lived to acquire freedom, equality of persecution had crushed their spirit, if it rights with Catholicism itself, wealth and had not killed their faith. When the the respect of men; she had reached Revolution gave them freedom, it also what would have seemed a time of threw them into political rather than relimillennial bliss to the hunted Huguenots;gious work. Then came their acceptance |