a a eee ee 
ES DESDE MECN eS SPO Pe ee 
Stir John Lubboch’s Address. 347 
which sometimes reach the earth as aérolites. 
Some light has also been thrown upon those mysterious visi- 
tants, the comets. e researches of Prof. Newton on the 
bodies similar in character and composition to the stony masses 
at any rate groups of meteoric stones. From the spectra of the 
small comets of 1866 and 1868, Huggins showed that part of 
their light is emitted by themselves, and reveals the presence of 
carbon in some form. A photographic spectrum of the comet 
recently visible, obtained by the same observer, is considered 
y him to prove that nitrogen, probably in combination with 
carbon, is also present. 
No element has yet been found in any meteorite, which was 
hot previously known as existing in the earth, but the phenom- 
ena which they exhibit indicate that they must have been 
formed under conditions very different from those which pre- 
vail on the earth’s surface. may mention, for instance, the 
peculiar form of crystallized silica, called by Maskelyne, Asma- 
nite; and the whole class of meteorites, consisting of iron gener- 
ally alloyed with nickel, which Daubrée terms holosiderites. 
The interesting discovery, however, by Nordenskiéld, in 1870, 
at Ovifak, of a number of blocks of tron alloyed with nickel 
and cobalt, in connection with basalts containing disseminated 
iron, has, in the words of Judd, ‘afforded a very important link, 
placing the terrestrial and extra-terrestrial rocks in closer rela- 
fons with one another.” 
mMineralogique.” Yet wi a few years what he supposed to 
be impossible has been actually accomplished, showing how 
Unsafe it is to limit the possibilities of science. _ 
It is hardly necessary to point out that, while the spectrum 
