224 LeVerrier on the constitution of the Solar System. 
We shall discuss, farther on, the consequences of this result, 
confirmed as it is, moreover, by a deduction from the theory of 
Venus. The increase in the latitude of this planet, leads us toa 
rigorous condition which can only be satisfied by augmenting 
the mass either of Venus, or of the earth. In publishing the 
theory of Venus, I had already remarked that the considerations 
referred to above, would not allow any change to be made 1 
the mass of Venus; that it appeared necessary therefore, to 
increase by a tenth part the mass of the earth; that in view of the 
importance of this conclusion, it were better, before deducing 
the consequences of it, to await the completion of the theory of 
Mars. Now, as we have just seen, the theory of Mars itself 
eee that we increase the mass of the earth by exactly a 
ten 
I should remark, before proceeding, that Mercury has already 
iven me a result of the same kind. Observation assigns to the 
perihelion of this planet a more rapid motion than that which 
corresponds to the masses above admitted. change of a 
tenth part in the mass of the earth, will not account for this fact; 
and as it is impossible to increase the received mass of Venus, I 
have hence inferred the existence of a ring of masses of matter 
_within the orbit of Mercury. The subject has already been dis- 
cussed, and will be still farther prosecuted; it may not be ul- 
profitable to repeat the language in which I announced my opin- 
1on (Annales, t. v, p. ‘ 
g a amis . 
contrary would be true, and, although the brilliancy of the disturbing 
y ; ess to the e 
perceived in ordinary circumstances.” ‘1 
“ But, even in this case, how could a large body having a great brit 
liancy and situated always near the sun have esca ing seen during cee 
some of the total eclipses? Finally, could such a body pass between the — 
. 
solar disk and the earth, and not be recognized 
single p: 
? a 
“Such are the objections which might be urged to the existence of 8 
) planet, comparable to Mercury as regards its dimensions, and re 
