ASTRONOMICAL PROGRESS AND DISCOVERY. 



55 



the air to the ground. 3. The perihelion-dis- 

 tances of nearly all the orbits in which these 

 stones move were not less than 0*5 nor more 

 than TO time the earth's radius. The author 



tee as fully proved the connection of 

 comets with meteors, and considers therefore 

 that the meteorites have velocities relative to 

 the sun not greater than 1-414 nor less than 

 1-244 time the earth's velocity in its orbit 

 (earth's orbital velocity 18-38 miles a second). 



Mr. Lockyer, in his paper read before the 

 Royal Society, Nov. 17, 1887, gives the result 

 of his experiments on meteorites. He ex- 

 amined meteoritic spectra under various con- 

 ditions, particularly that of feeble temperature. 

 He found it possible to obtain from meteorites 

 spectra that showed the most peculiar features 

 of almost every variety of spectrum solar, 

 star, nebular, and cometary. "In the spectra 

 of nebulas, for instance, seven lines have been 

 detected, of which three were traced to hydro- 

 gsn, three to low-temperature maguesium, 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 magne- 

 sium, and the unusual spectrum obtained from 

 the comets of 1866 and 1867 was ascribed to 



tme cause. The changes observed in the 

 spectrum of the great comet of 1882 were 

 such as would correspond to the changes in- 

 duced by the change of temperature in the 

 spectrum of a meteorite ; and the changes in 

 the spectrum of Xova Cygni, and the bright 

 lines in such a star as R. Geminorum received 

 a similar explanation ; while a very full, in 

 parts almost perfect, reproduction of a con- 

 siderable portion of the solar spectrum has 

 been obtained by taking a composite photo- 

 graph of the arc spectrum of several stony me- 

 teorites, taken at random between iron meteoric 

 poles. These and similar observations have 

 led Mr. Lockyer to regard ah 1 self-luminous 

 bodies in the celestial spaces as composed of 

 meteorites, or masses of meteoritic vapor pro- 

 duced by heat brought about by condensation 

 of meteor-swarms due to gravity, so that the 

 existing distinction between star, comets, and 

 nebula? rests on no physical basis. All alike 

 are meteoritic in origin, the differences between 

 them depending upon differences in tempera- 

 ture, and in the closeness of the component 

 meteorites to one another. Nora (new stars 

 that blaze forth suddenly) are explained as 

 produced by the clash of meteor-streams, and 

 most variable stars are regarded as uncon- 

 densed meteor - streams. Stars with sper-tra 

 like that of Alpha Orionis (Rigel) are con- 

 sidered not as true suns, but as mere clouds of 

 incandescent stones ; probably the first stage 

 of meteoritic condensation. Stars with spectra 

 of the first and second type represent the 

 condensed swarm in its hottest stages, while 

 spectra of Secchi's fourth type indicate an ad- 

 vanced stage of cooling." Objection has been 



i to Mr. Lockyer's hypothesis by M. 

 Stanislas Meunier. He contends that the only 

 conclusion we are as yet entitled to draw from 

 the spectroscopic researches on meteorites is, 

 that they are composed of the same original 

 matter as other celestial bodies. 



The Observatory of Milan has published Part 

 II, Xo. Y1I, of its observations. This last num- 

 ber contains a catalogue which is supplementary 

 to two preceding ones. The first (1874) con- 

 tained the observed paths of 7.152 meteors seen 

 in 1872 ; the second (1882) contained 7,602 me- 

 . and the present publication contains 9,627 

 meteors. 



Solar Physits. The experiments of Prof John 

 Trowbridge and C. C. Hutchius lead them to 

 conclude that there i? unmistakable evidence of 

 the existence of carbon vapor in the sun, and 

 that at the point of the sun's atmosphere where 

 the carbon is volatilized the temperature of the 

 sun approximates to that of the voltaic arc. 

 An exceedingly valuable contribution to sci- 

 ence has been made by C. C. Hutchins and 

 E. L. Holden in regard to the meaning of the 

 lines in the solar spectrum. They say that 

 "The dispersion given by the apparatus in the 

 order of spectrum in which we work is such 

 that a single wave-length occupies on the neg- 

 ative a space of 1*12 millimetres. This makes 

 the distance between lines Di and Da 6'7 milli- 

 metres. "We are convinced that there is much 

 in the whole matter of coincidences of metallic 

 and solar lines that needs re-examination ; that 

 something more than the mere coincidences of 

 two or three lines out of many is necessary to 

 establish even the probability of the presence 

 of a metal in the sun." They have examined 

 some of the doubtful elements in the list giveu 

 by Prof. Young in his book on "The bun." 

 and find, the evidence as f. Hows : For cadmi- 

 um, there were two perfect coincidences; for 

 lead, cerium, molybdenum, urai-ium, vanadi- 

 um, there was no good evidence in favor of 

 their existence in the sun. Among the metals 

 whose existence in the solar atmosphere has 

 seemed probable, their experiments seem to 

 show that bismuth and silver were present, but 

 that tin, potassium, and lithium were doubtful. 

 They also furnish evidence of the existence of 

 platinum in the sun, claiming that between 

 wave-lengths 4,250 and 4,950 to find 64 lines 

 of platinum, 16 of which agree with solar lines. 



Henry Crew has made some observations 

 with the spectroscope on the period of the ro- 

 tation of the sun. He obtained, for the mean 

 equatorial velocity, 2'437 miles a second, which 

 corresponds to a true period of rotation of 

 25-88 days. Mr. Crew thinks that, while the 

 sun-spot layer (or photosphere, if they be the 

 same) is accelerated in the neighborhood of the 

 equator, the layer, which by its absorption 

 gives rise to the Fraunhofer lines, tends to lag 

 behind, having here a smaller angular velocity 

 than in higher latitudes. Comparing the year 

 1886 with 1887, observers report that the aver- 

 age height of both the chromosphere and prom- 



