CO.MKT 



377 



\\ith scarcely a sign olmervable of the passage; 

 also Coggia's comet in 1874, remarkable for the 

 series of envelops of huninouH matter which 

 seemed to cumliine ti> form its tail. The great 

 comet of 1880 astonished astronomers ly follow- 

 ing the same track an that of 1843, almost gra/.iiit,' 

 the Mini. That of 1881 iii followed the track of 

 th.it of 1807, for a return of which it WHS ut first 

 mistaken. These two examples demonstrated that 

 in some cases several comets travel on 

 the same orbit, at great distances, 

 however, from one another. The 

 comet 1881 iii was the first success- 

 fully photographed, .lanssen obtaining 

 a picture including 2A, and Dr Henry 

 Draper of New York one including 

 10, of its tail. Dr Huggins and I)r 

 Draper were also both successful in 

 photographing its spectrum, with re- 

 sults confirming what eye observations 

 already had revealed. Dr Schiiberle 

 at Ann Arl>or, Michigan, discovered 

 another bright comet, the fourth for 

 the year 1881, which for a time accom- 

 panied 1881 iii, both being in the 

 northern heavens together. At Dud- 

 ley Observatory, U.S., a comparatively 

 small comet was discovered soon after 

 by Mr Wells, remarkable as the first 

 in whose spectrum the sodium line 

 was seen. In 1882 the surprise of i880 was 

 repeated. Another bright comet appeared in 

 September, following the tracks of the 1843 and 

 1880 comets, making the third in an orbital pro- 

 cession in space. It was seen in New Zealand 

 on September 3, at the Cape of Good Hope 

 on September 8, and at Rio de Janeiro on the 

 llth. Mr Common at London had been seeking 

 for a short time to catch a bright comet near the 

 sun in the daytime. Independently, on 

 September 17, he discovered this one, close 

 to and rapidly nearing the sun. Clouds 

 prevented him from seeing the passage, 

 but it was observed at the Cape of Good 

 Hope by Messrs Finlay and Elkin, who 

 were watching at the time. Passing in 

 front of the sun, it disappeared from view, 

 overpowered by the solar brilliance, to 

 reappear shortly passing off the other edge 

 of the disc. All next day it was clearly 

 seen, only surpassed in brilliancy by the 

 sun itself. Though it had passed so close 

 to the sun, it experienced no retardation 

 of speed, proving that very near the solar 

 surface there can be no resisting medium 

 of density to affect such a body. It was followed 

 with the telescope to a distance from the earth 

 of 470,000,000 miles. This long observation en- 

 abled its period to be well ascertained as alxmt 

 700 years. It exhibited in a marked degree a ten- 

 dency to disruption. ' Space appeared,' says Mi 

 Clerke, ' to be strewn with the filmy debris of this 

 extraordinary body all along the track of its retreat 

 from the sun.' Its tails corresponded to types 1 

 and 2 ( see post ), and there was a vast outburst of 

 luminous matter in October touwds the sun, having 

 a diameter of 4,000,000 miles. Its spectrum showed 

 the sodium line in addition to the usual cometary 

 bands. The year 1883 was barren in cometary 

 results ; 1884 saw three new comets discovered 

 respectively in Tennessee, Australia, and Euro] \>\ 

 Barnard, Ross, and Wolf. In 1885, on the 27tli 

 November, there was a grand display of the meteors 

 into which Biela's comet is now generally considered 

 to have broken up ; 50 to 60 a minute being 

 recorded. Brooks, of Phelps, New York, discovered 

 a comet on August 31 in that year. But in the 

 next year (1886), within two months, three comets 



rewarded thia diligent observer, a record equalled in 

 1887 by Barnard, of Nashville, Tcnnemee. In 1888 

 comets were discovered by Sawerthal on February 

 18, and by Brooks, New York, on August 7. The 

 n i m MS of Encke's comet and of Kaye's comet alao 

 marked that year, as they again did the year 1895, 

 in which De Vico's comet wan seen for the first 

 time since 1844. Seven new comets were seen for 

 the first time between Nov. 1895 and Nov. 1896. 



Comet of 1811. 



The quantity of matter in even the largest comet 

 is known to be very small, ^uVtr or so of that of the 

 earth in a calculated instance, much less probably 

 in many others. The nucleus, in which most of 

 this is contained, is generally admitted to be a more 

 or less close congeries of meteoric fragments. This 

 is shown by the smallness of its mass as compared 

 with its size, its spectrum, and the fact that comets 

 and meteors follow one another in similar orbits. 



Donati's Comet, 1868. 



Biela's lost comet is now probably scattered into the 

 meteor stream which pursues its track (see ante). 

 The close agreement of cometary and meteoric or- 

 bits may appear from the fact that Tempers comet 

 (1866) has a period of 33 '28 years, and the three 

 groups of November meteors, following the same 

 line, periods respectively of 32*25, 33-31, and 33'11 

 years. Also just as these groups follow one another 

 in procession round the sun, so do the comets aln>ve 

 mentioned of 1843, 1880, and 1882. Other systems 

 of mingled comets and meteors are also known, and 

 the spectroscopic researches of Lockver may be said 

 to have demonstrated that the peculiar spectrum of 

 comets can be produced from meteors. Carbon, 

 hydrogen, and sodium have been shown to enter 

 into the composition of cometary nuclei. A banded 

 spectrum of a hydrocarlton is the usual type, the 

 sodium line only showing when the nucleus is close 

 to the sun, and sweeping rapidly past it in a state 

 of great disturbance. Usually as the nucleus nears 

 the -mi. it appears disturlied; then jets or masses of 

 liimiiiou- material, gas or fine dust, are thrown up. 

 Some repulsive force appears to seize these and 



