1859.] l>r, Gladstone on the Colours of Shooting Stars, 148 



Thus, both the modes of investigation which had been described, 

 lead to like conclusions respecting the least thickness which can be 

 assigned to the solid envelope of our globe. It must be much greater 

 than geologists have frequently imagined it to be. 



[W.H.] 



WEEKLY EVENING MEETING, 



Friday, May 20, 1859. 



Henry Bence Jones, M.D. F.R.S. Vice-President, in the Chair. 



John Hall Gladstone, Ph.D. F.R.S. M.li.I. 

 On the Colours of Shooting Stars and Meteors, 



All are familiar with the smaller kinds of shooting stars, and mo»t 

 have observed those of a larger size which shoot across the sky like a 

 rocket, and burst perhaps in a shower of sparks ; many persons also 

 have been witnesses of the grander displays called fire-balls, or bolides, 

 and some few have seen those bright clouds that have occasionally 

 appeared and rained down stones upon the earth. It is not cer- 

 tain that all these are connected phenomena, or that there is a solid 

 nucleus to every shooting star; yet it is impossible to draw any 

 exact line of distinction, and there is every gradation between the 

 most striking and the most simple of these appearances. The investi- 

 gations of scientific men have made us acquainted with many fact* 

 relating to these bodies : thus, their direction is never perpendicular to 

 the earth, but more frequently almost horizontal, and though they fly 

 from every quarter of the heavens, the majority come from that part 

 towards which the earth is at the time moving ; their velocity averages 

 about 20 miles per second ; their height above the earth is, of course, 

 very various, yet the more brilliant fire-balls seem to begin their 

 luminous feurse at somewhere about 40 miles above us ; their size is 

 probably small in all instances, although, from irradiation, they fre- 

 quently appear to present a considerable diameter ; they occur often in 

 showers ; and these showers have been observed to have an annual 

 periodicity. At the present time these star-showers occur generally 

 about August 10 and November 13, but at the end of the 11th cen- 

 tury the most remarkable period was April 4 ; and those wonderful 

 people the Chinese, who have kept records of showers of meteors since 

 March 23, B.C. 687 (when Manasseh was ruling over Judah, and 

 European history scarcely existed) tell of other periods, pre-eminent 

 among which is July 22. 



The meteorolites which fall from the sky are of two sorts ; the 

 stony, consisting of silicate of magnesia, with more or less admixture of 

 lime, potash, or soda combined with silicic acid ; and the metallic, 



