Jan. 24. T878] 



NA TURE 



247 



describe it as being nearly as large as the full moon and 

 greatly exceeding it in brilliancy. An observer at Ashby- 

 de-la-Zouch first noticed his shadow, and those of neigh- 

 bouring trees thrown towards the moon, then shining 

 brilliantly in the east. Persons much nearer the scene, 

 sitting in rooms with the blinds down, were frightened 

 by the flood of light that suddenly found its way in. The 

 meteor exploded with great violence at the height of 14 

 miles over the Irish Sea, 20 miles N.N.W. (true) of 

 Llandudno. The total length of path was 135 miles, 

 which was traversed in about 8 seconds of time, or with a 

 velocity of 17^ miles per second, as determined from 

 twenty-three estimations of its duration. 



The streak left in the air extended for 40 miles along 

 the track, and was not less than 2,000 feet in diameter. 



The violence of the explosion was such, that at Bangor, 

 Beaumaris, Conway, and Llandudno, doors and windows 

 rattled, and people ran out to see what was the matter. 

 As far as Chester the sound resembled " thunder not very 

 far distant," or " a salvo of artillery." 



It is a fact worthy of thoughtful consideration that the 

 body which was capable of producing this convulsion, pro- 

 bably exceeding the discharge of the 81-ton gun in the 

 proportion of a hundred to one, was converted into im- 

 palpable powder in eight seconds of time, merely by the 

 rapidity of its transmission through very attenuated air. 

 After the explosion nothing remained but dully incan- 

 descent dust or ashes, which slowly fell a short distance 

 vertically downwards. That is to say, there was not 

 one remnant sufficiently heavy to continue in the same 

 direction, or to retain the original velocity, because such a 

 remnant would have been visible itself as a bright meteor. 

 A momentum which, estimated in foot-tons, would reach 

 some enormous figure, was instantaneously reduced to 

 nothing, or, rather, converted into atmospheric waves — 

 and dust ! 



The exact position and height of the explosion is fixed 

 by the singular observation of Mr. Petty, at Llandudno 

 (Nature, vol. xvii, p. 183), who did not even see the 

 meteor itself, but its light on the hearthrug coming 

 through a chink in the blind. 



Mr. J. Ismay, the superintendent of telegraphs at 

 Liverpool, who observed the explosion from the beach 

 at Llandudno, measured the sound-interval, and found it 

 between 2 min. and 2 min. 15 sees. From the spot where 

 I have assumed the explosion took place to his position 

 is 25 miles, which sound would traverse in two minutes 

 exactly. 



The orbit deduced from the apparent position of the 

 radiant point is — 



?■ = o 

 " = 153° 

 ?.= '47 

 Motion direct. 



The relative velocity obtained by assuming a parabolic 

 orbit is 19 miles per second, agreeing very closely with 

 that found by observation. 



If the longitude of the radiant be diminished 3" or 

 4°, the orbit is so far modified as to almost coincide 

 with that of the comet of 1702. The comet was not very 

 well observed. The meteor belonged to the well- 

 known shower of Taurids, first discovered by Mr. R. P. 

 Greg, encountered by the earth with great regularity about 

 November 21-23. In 1877 it appears to have been very 

 prolific of bright and of detonating meteors. 



G. L. TUPMAN 



OUR ASTRONOMICAL COLUMN 



The Comets of 1618.— The year 1618 presented a 

 phenomenon which is perhaps unique in the history of the 

 appearances of comets, two of these bodies having been 

 conspicuously visible at the same time in certain parts of 

 he earth, and for several days, at least, in the same 



quarter of the heavens, with trains of thirty or forty 

 degrees in length, and upwards. Cometographers pre- 

 vious to Pingr^ had been much exercised with reference 

 to the comets of this year ; Comiers, in " La Nature et 

 Prestige des Cometes," had supposed that six comets in 

 all were observed in 16 18 ; this number was reduced by 

 Pingr^ to three, which appears to have been beyond 

 doubt the correct number, though another cometographer, 

 Struyck, disputed the distinctness of Pingrd's second. 



The first comet was discovered at Caschau, in Hungary, 

 on August 25, and two days later by Kepler, at Lintz, 

 where it rose in the morning about three o'clock, with a 

 tail directed towards the west. Kepler observed it on 

 several occasions, and for the last time on the morning of 

 September 25, and from his rough indications of its 

 positions Pingrd calculated the elements which figure in 

 our catalogues, and which it will be found represent the 

 track of the comet pretty nearly ; there can be no con- 

 fusion between this object and the second or third comets 

 of the year. 



The third comet, as Pingrd remarks, " eut autant 

 d'observateurs qu'il y avoit alors d'astronomes en Eu- 

 rope." It was first seen in Europe in the last days of 

 November, and was observed by Cysat at Ingoldstat till 

 January 21, he having used optical aid, though other 

 observers lost it at the beginning of the month, or even 

 earlier. The elements, first calculated by H alley, were 

 more accurately investigated by Bessel, whose orbit, 

 published in 1805, agrees with the observations as closely 

 as the errors, with which they are obviously affected, will 

 allow. There is no difficulty, therefore, in fixing upon the 

 position of the third comet, with sufficient approximation 

 in the month of November previous to its discovery in 

 Europe. 



It appears to have been one of the finest comets of the 

 seventeenth century, apparently hardly exceeded in the 

 imposing character of its appearance by the celebrated 

 comet of 1680. The tail gradually increased in length 

 until, on the morning of December 10, the Danish 

 astronomer, Longomontanus, estimated its extent at 104% 

 with marked coruscations. 



The second comet of 16 18, according to Pingr^, to 

 which these remarks are intended more particularly to 

 refer, was discovered in Silesia, and also at Rome, on the 

 morning of November i r, as Kepler tells us {De Cometis 

 lib. /.). The nucleus was lost in the twilight, but the tail 

 was visible from 4h. 20m. to 6h. 40m. at Rome. On the 

 following mornings the tail was seen at other places in 

 Europe, and by Kepler himself at Lintz, at 5h. 30m. A.M. 

 on November 20 ; he then describes it as a train of milky- 

 white light, passing below the stars in the quadrilateral of 

 Corvus, and reaching the extremity of Crater. He saw 

 this train for the last time on the morning of November 

 29, when " inter atras nubes et ventos vehementes, cum 

 campi essent picti nivula, apparuit tamen tractus iste. 

 secundi cometae, sed valde dilutus nee aequans albedinem 

 nubium a luna illuminatarum." This was at 5 A.M., and 

 an hour and a half later, the clouds having somewhat 

 dispersed, he obtained his first view of the third comet, 

 which was then in longitude 221°, with between 9° and 

 10° north latitude. Thus we see that Kepler saw both 

 comets on the same morning, though he failed to detect 

 the nucleus of the second in the strong twilight ; and it 

 may be added that Blancanus, at Parma, had similar 

 experience. 



In more southern latitudes the second comet was pretty 

 favourably situated for observation, and its nucleus was 

 observed. Figueroes, ambassador of Spain, at Ispahan, 

 and the Jesuits at Goa, saw both comets simultaneously, 

 and determined positions of the nucleus of the second. 

 Riccioli mentions that Father Kirwitzer, an Austrian, was 

 sent out to China, and died at Macao in 1626, adding 

 that he wrote of observations made in India on the 

 comets of 161 8. 



