Nov. 17, 1887] 



NATURE 



55 



RESEARCHES ON METEORITES. 

 I. 



ON October 4 I communicated to the Royal Society a 

 preliminary note embodying some results I had 

 obtained in observations on meteorites, undertaken with a 

 view of obtaining additional information on some parts of 

 the spectrum of the sun. 



Some years ago I commenced a research on the 

 spectra of carbon in connection with certain lines I had 

 detected in my photographs (1874) of the solar spectrum. 

 I have been going on with this work at intervals ever 

 since ; and certain conclusions to which it leads, em- 

 phasizing the vast difiference between the chemical 

 constitution of the sun and of some stars, recently 

 suggested the desirability of obtaining observations of the 

 spectra of meteorites and of the metallic elements at as 

 low a temperature as possible. 



I have latterly, therefore, been engaged on the last- 

 named inquiries. The work already done, read in con- 

 junction with the work on carbon, seems to afford evidence 

 which amounts to demonstration on several important 

 points. 



The researches are still very far from complete, and 

 the results must be given with great reserve, as the 

 astronomical observations with which I have had to com- 



pare my laboratory work have been frequently made 

 under conditions of very great difficulty. 



A full report on the work, so far as it has gone, made to 

 the Solar Physics Committee, which I have also com- 

 municated to the Royal Society, was read to-day, and I 

 have received permission to publish part of it in this 

 week's Nature. 



The general conclusions at which I have so far arrived' 

 may be stated as follows : — 



I. All self-luminous bodies in the celestial spaces are com- 

 posed of meteorites, or masses of meteoritic vapour produced by 

 heat brought about by condensation of meteor-swarms due to 

 gravity. 



II. The spectra of all bodies depend upon the heat of the 

 meteorites, produced by collisions, and the average space between 

 the meteorites in the swarm, or in the case of consolidated swarms 

 upon the time which has elapsed since complete vaporization. 



III. The temperature of the vapours produced by collisions in 

 nebuloe, stars without C and F but with other bright lines, and 

 in comets away from perihelion, is about that of the bunsen 

 burner. 



IV. The temperature of the vapours produced by collisions in 

 a Orionis and similar stars is about that of the Bessemer flame. 



V. The line of increase of temperatures of the swarms of 

 meteorites, and of subsequent cooling of the mass of vapour pro- 

 duced, and the accompanying phenomena, may be provisionally 

 stated as follows : — 



Sequences of Spacing and Temperatures (Provisional) 

 From Cold to Hot = Sparse to Dense Swarms. 



Nebulas (without F) 



Comets 1866 and 1867 



Nova Cygni after collision 

 Stars with bright lines (without F) 

 Nebulae (with F) 



Stars with bright lines (with F). 



Comets under mean conditions 



of collision 



Comets at perihelion 



Stars, Class III. a 



Mixed swarms — 



R Geminorum 



Nova Orionis at maximum. 



Spectrum of interspace. Spectrum of vapour of meteorite. 



H. C. 



Radiation. Absorption. 



... Nil Nil Mg (500) ±495 



.. Nil Nil Mg (500) \ Nil? 



... Nil Nil Mg(5oo) 



Nil Nil Fe, Mn 



H Nil Mg (500) ± 495 



..S 



H 



I Nil 



Nil 

 Nil 



H 

 H 



Nil 



C 

 C 



c 



c 

 c 



Condensation. 



Stars, Classes I. and II 



Subsequent Cooling. 

 Q / Class II. some stars, including sun 

 ^^^'"H Class 111.(5 



Fe, Mn 



Mg(^) 



Meteorite lines . 



Meteorite lines 

 Continuous 



Broad band 475 



Nil? 

 D and b and other lines 

 and bands 



Nil. 



(?) 



Meteorite flutings and lines 



/ Meteorite lines 



\ Meteorite flutings and lines 



! High-temperature lines of ' 

 substances present i 

 meteorites 



:;;} 



Continuous 



...{ 



K in excess ... 

 Flutings of carbon 



Spectrum of meteorite. 

 Radiation. 



Dimly continuous. 



Continuous, 



Continuous. 



Vividly continuous. 



The radiation from individual meteor- 

 ites now gives place to radiation 

 from the interior vaporous and sub- 

 sequently consolidated mass of the 

 condensed swarm. 



VI. The brilliancy of these aggregations, at each (increasing) 

 temperature, depends on the number of meteorites in the swarm 

 — i.e. the diff'erence depends upon the quantity, not the intensity, 

 of the light. 



VII. The existing distinction between stars, comets, and 

 nebulas rests on no physical basis. 



VIII. The main factor in the various spectra produced is the 

 ratio of the interspaces between the meteorites to their incand- 

 escent surface. 



IX. When the interspace is very great, the tenuity of the 

 gases given off" by collisions will be so great that no luminous 

 spectrum will be produced ("nebulae" and "stars" without F 

 bright). When the interspace is less, the tenuity of the 

 gas will be reduced, and the vapours occupying the inter- 

 spaces will give us bright lines or flutings ("nebulae" and 

 " stars " with F bright). When the interspace is relatively small, 

 and the temperature of the individual meteorites therefore 

 higher, the preponderance of the bright lines or flutings in the 

 spectrum of the interspaces will diminish, and the incandescent 

 vapour surrounding each meteorite will indicate its presence by 

 absorbing the continuous-spectrum-giving light of the meteorites 

 themselves. 



X. The brighter lines in spiral nebulae, and in those in 

 which a rotation has been set up, are in all probability 

 due to streams of meteorites with irregular motions out of 

 the main streains, in which the collisions would be almost 

 nil. It has aleady been suggested by Prof. G. Darwin^ 

 — using the gaseous hypothesis — that in such nebiilte " the 

 great mass of the gas is non-luminous, the luminosity being 

 an evidence of condensation along lines of low velocity 

 according to a well-known hydrodynamical law. From this point 

 of view the visible nebula may be regarded as a luminous 

 diagram of its own streamlines." 



XI. New stars, whether seen in connection with nebulae or 

 not, are produced by the clash of meteor swarms, the bright 

 lines seen being low-temperature lines of elements the spectra of 

 which are most brilliant at a low stage of heat. 



XII. Most of the variable stars which have been observed 

 belong to those classes of bodies which I now suggest are un- 

 condensed meteor-swarms, or stars in which a central more 

 or less solid condensed mass exists. In some of those having 

 regular periods the variation would seem to be partly due to 



' Nature, vol. x\xi. p. 25. 



