154 RECORD OP SCIENCE FOR 1887 AND 1888, 



Prof. Daniel Kirkwood bas suggested that ceitaiu comets of sliort 

 period may have origiuated withia the solar system. Wolf's comet 

 (1884 III), for example, before its last near aj^proach to Jupiter, had au 

 eccentricity of 0.28, Avhicb is exceeded by twelve known asteroids, and 

 the elements of Tempel's comet (1867 II) do not differ greatly from 

 those of au eccentric asteroid. Out of twenty short-period comets, 

 seven have disappeared either by dissolution, like Biela's comet, or by 

 the transformation of the orbit by Jupiter as in the case of LexelFs comet. 

 Five, or, including Encke's and Biela's, seven, have periods commensur- 

 able with that of Jupiter; all have direct motion; all but one have a 

 smaller inclination than Pallas, and there is a tendency of the perihelia 

 to concentrate in the 180° (from 290° to 110^), as in the asteroids. 



One of the most able of recent contributions to cometary astronomy 

 is a monograph by Dr. Kreutz upon the orbit of the great September 

 comet of 1882. In connection with investigations being carried on by 

 Professor Weiss this will form a comi)lete discussion of the system of 

 comets with remarkably small perihelion, distance, 1843 I, 1880 I, and 

 1882 II. 



Dr. Galle is compiling a catalogue of recent comets embracing the 

 various sui>plements to the list given in 1847 in Encke's edition of 

 " Olbers' Methode." 



METEORITES. 



Researches on meteorites. — Mr.Lockyer presented at the meeting of the 

 Eoyal Society on November 17, 1887, a paper giving the results of his 

 *' Researches on Meteorites," which has attracted much attention. He 

 has examined meteoric spectra under various conditions, i)articularly 

 that of feeble temperature, and has found it possible to obtain from 

 meteorites spectra that show the most peculiar features of solar, stellar, 

 nebular, or cometary spectra. " In the spectra of nebuhne, for instance, 

 seven lines have been detected, of which three were traced to hydrogen, 

 three to lowtemj)erature magnesium, and the seventh, which has not 

 yet been traced to its originating element, has been given by the glow 

 from the Dhurmsala meteorite. The most characteristic nebular line 

 was identified with the low-temperature liutiug of magnesium, and the 

 unusual spectrum obtained from the comets of 1866 and 1867 was 

 ascribed to the same cause. The changes observed in the spectrum of 

 the great comet of 1882 were such as would correspond to the changes 

 induced by the change of temperature in the spectrum of a meteorite; 

 and the changes in the spectrum of Nova Cygni, and the bright lines in 

 such a star as E Geminorum received a similar explanation ; wliile a 

 very full, in parts almost perfect, reproduction of a considerable portion 

 of the solar spectrum has been obtained by taking a conu^osite photo- 

 graph of the arc spectrum of several stony meteorites, taken at random 

 between iron meteoric poles. These and similar observations have led 

 Mr. Lockyer to regard all self-luminous bodies in the celestial spaces 



