SECTION I. COMETS WHICH HAVE APPROACHED NEAREST TO THE EARTH. The memoir of Lalande and the panic of the year 1773--Letter of Voltaire upon the comet-Announcement in the Gazette de France and the Memoirs of BachaumontCatalogue given by Lalande of comets which up to that time had approached nearest to our globe. In the spring of the year 1773 a singular rumour, soon followed by a strange panic, obtained in Paris and rapidly spread throughout France. A comet was shortly to appear upon the earth's track, to come into collision with our planet, and thus infallibly bring about the end of the world. The origin of this rumour was a memoir which Lalande was to have read before the Academy of Sciences on April 21; it was, however, not read, but the title alone was sufficient to create a popular ferment. The work of the learned astronomer was entitled Réflexions sur les Comètes qui peuvent approcher de la Terre. It was speedily imagined, and without the smallest foundation—for nothing of the kind was to be found in the memoir-that a comet predicted by the author was about to dissolve the earth on May 20 or 21, 1773. So great was the panic that Lalande, before publishing his work, caused the following announcement to be inserted in the Gazette de France of May 7: M. de Lalande had not time to read a memoir on the subject of the comets, which by their approach to the earth may occasion disturbance to it; but he observes that it is not possible to fix the date of these events. The next comet whose return is expected is that which is due in eighteen years, but it is not amongst the number of those which can harm the earth.' This notice, it appears, did not allay the public uneasiness, for, under the date of May 9, we read the following in the Mémoires de Bachaumont: 'The cabinet of M. de Lalande is still besieged by the curious, anxious to interrogate him upon the memoir in question, and doubtless he will give to it a publicity which is now necessary, in order to reassure those whose heads have been turned by the fables to which it has given rise. So great has been the ferment that some dévots, as ignorant as they are foolish, solicited the archbishop to have a forty hours' prayer, in order to arrest the enormous deluge threatened; and that prelate was on the point of ordering the prayer, when some Academicians made him sensible of the absurdity of such a proceeding. The false announcement in the Gazette de France has created a bad effect, for it is believed that the memoir of the astronomer must have contained terrible truths, since they were thus evidently disguised.' We see that a century ago communiqués were not more efficacious than at the present day, and were just as much believed. But the expressions which Bachaumont uses in regard to the dévots are not more misplaced than the abuse which he finds means further on to lavish upon Lalande. How much more to the point is the refined irony of Voltaire in his Lettre sur la prétendue Comète! Let the following short extract speak for itself: 'Grenoble, May 17, 1773. 'Some Parisians, who are no philosophers-and, if they are to be believed, will not have time to become so-have informed us that the end of the world is approaching, and that it will infallibly take place on the 20th of this present month of May. 'On that day they expect a comet which is to overturn cur little globe and reduce it to impalpable powder, according to a certain prediction of the Academy of Sciences which has not been made. 'Nothing is more probable than this event; for James Bernoulli, in his "Treatise upon the Comet," expressly predicted that the famous comet of 1680 would return with a terrible crash on the 17th of May, 1719. He assured us that its wig would signify nothing dangerous, but that its tail would be an infallible sign of the wrath of heaven. If James Bernoulli has made a mistake in the date, it is probably by no more than fifty-four years and three days. 'Now, an error so inconsiderable being looked upon by all mathematicians as of no account in the immensity of ages, it is clear that nothing is more reasonable than to expect the end of the world on the 20th of the present month of May, 1773, or in some other year. If the event should not happen, what is deferred is by no means lost. 'There is certainly no reason to laugh at M. Trissotin when he says to Madame Philaminte (Femmes Savantes, act iv., scene 3): Nous l'avons en dormant, madame, échappé belle: Un monde près de nous a passé tout du long, Elle eût été brisée en morceaux comme verre. There is no reason whatever why a comet should not meet our globe in the parabola which it is describing; but what then would happen? Either the force of the comet would be equal to that of the earth or it would be greater or less. If equal, we should do it as much harm as it would do us, action and reaction being equal; if greater, it would take us along with it; if less, we should take it along with us. 'This great event can be managed in a thousand ways, and no one can affirm that the earth and the rest of the planets have not experienced more than one revolution from the embarrassment of a comet encountered in its way.' Lalande's memoir was published in the course of the year 1773. It appeared moreover in the Comptes rendus of the Academy, and the prediction which had never been made was soon forgotten. The Parisians will not desert their city,' says Voltaire, in concluding his letter; 'they will sing their chansons, and the "Comet and the End of the World" will be played at the Opéra Comique.' What, then, after all, was the purpose of Lalande's work? To find by calculation the distances of the nodes of sixty-one comets from the earth's orbit, as well as the distances of these comets from the ecliptic, when the comet's radius vector was equal to unity. By means of these elements it was possible to determine which among known comets could most nearly approach the earth, and, consequently, occasion or undergo the greatest perturbations. The table which he gave was perfected by a Swedish astronomer, Prosperin. The following extract contains the most curious of the results: |