OBSERVATIONS OF LUMINOUS METEORS. 225 



boldt and Quetelet as belouging to the Jfovember stream, indicated the 

 existence of two distinct and widely separated chisters moving in orbits very 

 nearly identical. The years thus designated were 17S7, 1818, 1820, 1822, 

 1823, 1841, and 1846. As the last two were subsequent to the great 

 display of 183.3, the meteors seen were noticed only in consequence of their 

 being specially looked for ; and as the number conformable to the radiant 

 of the Leonids is not given, there may be some doubt whether those observed 

 really belonged to the November stream. The former displays occurred 

 before the periodicity of such phenomena had been suspected, and the 

 number of meteors would seem to have been considerable. As the shower 

 of 1787 preceded by twelve years the great meteoric fall witnessed in South 

 America by Humboldt, the group from which it was derived had passed 

 beyond the orbit of Saturn at the time of the latter display. The pheno- 

 mena of 1818, 1820, 1822, and 1823 indicate that, as in the case of the 

 major group, which passed its descending node between 1865 and 1870, the 

 meteoroids are extended over a considerable arc of their orbit. From No- 

 vember 1787 to the middle of the nodal passage of 1818-1823 is about 33^ 

 years — a period nearly the same as that of the principal cluster. These 

 facts alone were regarded by the present writer as giving reasonable pro- 

 bability to the h3'pothesis of an approximate identity of orbits. In ' Nature,' 

 vol. xi. p. 407, it was shown that the meteor-showers of October 855 and 

 856 were probably derived from the stream of Leonids* ; and it is certainly 

 remarkable that the interval from 855 to 1787 is equal to twenty-eight 

 periods of 33-293 years. Again, the shower observed in China, Sept. 28, 

 A.D. 288, making proper allowance for the nodal motion, corresponds to the 

 same epoch, the interval between 288 and 855 containing seventeen periods 

 of 33-35 years. In view of the fact that the shower from this cluster was 

 due between 1851 and 1855, the following extract from the writer's note- 

 book is not without interest : — 



" ' Newark, Delaware, Nov. 13, 1852. ... On the evening of the 11th, 

 from 7 to 10 o'clock, an aurora borealis of ordinary brilliancy was constantly 

 observed. About midnight the sky became overcast with clouds, thus pre- 

 venting our watch for meteors which we were about to commence. On the 

 12th, from about 3 to 9 o'clock a.m., rain fell almost incessantly. About 

 noon the clouds broke away, and the night between the 12th and 13th was 

 quite clear. During six hours (from 10 p.m. to 4 a.m.) constant watch was 

 maintained at four windows, facing north, south, east, and west. From 

 10 to 1 o'clock the observations were conducted by Prof. Ferris and myself 

 with assistants. At 1 the place of Prof. Ferris was taken by Prof. Porter, 

 who remained, with myself and assistants, till 4. "We observed — 



* The first of these showers is recorded by an Arabian chronicler, and also as follows hi 

 the 'Aiuiales Fuldenses': — "Per totam noctem igniculi instar spiciilorum occidentem 

 versus per aerem densissime ferebantur." That of the foUowing year (856) is cited from 

 similar but somewhat less authentic sources in Quetelet 's Catalogue, and is suspected to be 

 identical with it. By comparing the dates of these two showers with that of the famous 

 one which took place in 1306 (a year, as well as the year 868, in which the comet accom- 

 panying this star-shower was also seen : vide these Eeports for 1873, p. 401), Boguslawski 

 first suspected an advance in the node of the meteor-orbit before its real form and period 

 had yet been detected. But the showers of 855-56 preceded by 12years the regular periodic 

 shower of 868 ; and it is remarked by Professor Kirkwood that this divergence of their 

 dates agrees exactly with the interval by which the weU-marked November showers of 1820 

 and 1822 antieiiiated the appearance of the celebrated star-shower of November 13th, 1833. 

 (' Nature,' sup. cit., March 25th, 1875.) 



1875. a 



