154 HECORD OF SCIENCE FOR 1887 AND 1888, 



Prof. Daniel Kirkwood has suggested that certain comets of short 

 period may liave originated within the solar system. Wolf's comet 

 (1884 III), for example, before its last near approach to Jupiter, had an 

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

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

 those of an 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 Lexell's 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 complete discussion of the system of 

 comets with remarkably small perihelion distance, 1813 I, 1880 I, and 

 1882 II. 



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

 various supplements 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 

 Royal Society on Nov^ember 17, 1887, a paper giving the results of liis 

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

 has examined meteoric spectra under various conditions, particularly 

 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 uebul;i% for instance, 

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

 three to low- temperature 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 fluting of magnesium, and the 

 unusual spectrum obtained from the comets of 1806 and 1807 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 Kova Oygni, and the bright lines in 

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

 very full, in parts almost perfect, reproduction of a considerable i)ortion 

 of the solar spectrum has been obtained by taking a composite photo- 

 grai)h 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 



