SCIENTIFIC SUMMAET. 
265 
part of the spectrum to which it corresponds in refrangihility. A more 
careful examination Avith a narrower slit shoAved that, a little more refrangible 
than the bright line, and separated from it by a dark interval, a narrower 
and much fainter line occurs. Beyond this again, at about three times the 
distance of the second line, a third exceedingly faint line was seen. The 
position of these lines in the spectrum Avas determined by a simultaneous 
comparison of them with the spectrum of the induction spark, taken from 
electrodes of magnesium. The strongest line corresponds in position with the 
brightest of the air lines ; this line is due to nitrogen, and occurs in the 
spectrum about midAvay between h and F of the solar spectrum. The faintest 
of the- lines in the spectrum agrees in position with the line of hydrogen 
corresponding to Fraunhofer’s F. The other bright line Avas compared with 
the strong line of Barium 2,075 ; this line being, however, a little more re- 
frangible than that belonging to the nebula. Besides these lines an exceed- 
ingiy faint spectrum was just perceived for a short distance on both sides 
of the group of bright lines. This the authors suspect to be not uniform, but 
crossed with dark spaces. This faint spectrum they attribute to the solid or 
liquid matter of the nucleus, and as being quite distinct from the bright 
lines into which nearly the whole of the light from the nebula is resolved. 
The conclusion at which these physicists arrive from the above observations 
is, that the nebulae in question can no longer be regarded as clusters of suns 
similar in constitution to the centre of our planetary system, but as objects 
having quite a different and peculiar composition. Instead of being con- 
sidered bodies having a solid nucleus, three nebulae must now be regarded as 
enormous masses of luminous gas or vapour ; for it is alone from matter in 
the gaseous state that light consisting of definite refrangibilities only (as in 
the case with those nebulae) is known to be emitted. The gaseous matter 
would seem to be composed of these elements — nitrogen, hydrogen, and a 
substance unknown. With the exception of nitrogen, the writers state that 
not one of the thirty elements, the spectra of which have been measured, has 
a strong line very near the bright line of the nebulae. If, however, this line 
j were due to nitrogen, other lines should be seen, for there are specially two 
i strong double lines in the spectrum of nitrogen, one at least of which, if it 
■ existed in the light of the nebulae, would easily be seen. This exceptional , 
1 appearance Messrs. Huggins and Miller explain upon the supposition that 
;i possibly the single line may indicate a form of matter more elementary than 
nitrogen which our analyses have not yet enabled us to reach. The generali- 
1 zation which these gentlemen have formed is based upon the most careful 
^ and unquestionable investigations, and appears to be in some measure cor- 
ij roborative of what it has been customary till now to term the Avild specu- 
: lations of Laplace. — Vide Report of Messrs. Huggins and Millet' in The 
Chemical JSIeics, Nov. 26th. 
I Relation between Electrical Intensity and Surface. — Sir W. SnoAv Harris, 
j F.K.S., has done good service to the department of electricity, by publishmg 
I the various .laws, the formulation of which, from his numerous observations, 
i was given in his memoir, j>resented some time since to the Eoyal Society. 
I His remarks upon the complex question of the relation of intensity to 
I surface, are of decided interest. If (he says) three or more separated equal 
I spheres be charged with three or more equal quantities of electricity, and be 
