393 
when a man rides through a forest, all the trees at different 
distances on each side of him will necessarily appear to move 
relatively to one another as he advances. If, however, only 
one or two trees here and there appeared to move to a man in 
the midst of a forest, while others behind them remained sta- 
tionary, the man ought to be sure of two things : first, that 
the apparent motion of these few trees must be more or less 
real ; and, 2nd, that at any rate, and whatever the cause of 
their apparent motion might be, he is not moving through the 
forest himself. 
25. But in the next place, the whole speculation and all the 
computations in connection with it, were further vitiated, and 
absurd ab initio, from the very calculations as to the parallax 
of those stars having an apparent proper motion, being made 
upon the self- contradictory supposition that they were viewed 
every six months from the ends of a base line only 190 millions 
of miles long, — that is, from the extreme ends of the diameter of 
the earth’s orbit round the sun, which base was only accurate 
upon the hypothesis that the sun is at rest and not moving in 
space ! But I cannot now spare further time to point out all 
the absurdities connected with this ridiculous and now aban- 
doned theory, but must refer to what I have published else- 
where on the subject.* 
26. After the fixed stars the next astronomical objects that 
must engage our attention are the planets, with their satel- 
lites, — including our own moon, upon the current theory which 
regards the earth as also a planet revolving round the sun. Con- 
sidering the theory of solar motion in space as now virtually 
given up by the Astronomer Royal, I shall not here notice further 
the confusion and complications and contradictions that theory 
necessarily introduced into the planetary theory as believed in 
by Kepler and Newton, but will only refer to preceding para- 
graphs (§§ 7, 10, 13, 15,) of this paper, and to what I have 
previously written elsewhere on the subject. f But the fact is, 
many of the difficulties and complications which the theory of 
solar motion in space, if accepted, would introduce into the 
current planetary theories, do already exist with respect to the 
motions of the satellites of the various planets. And this con- 
sideration obliges me to revert to the two astounding and 
illogical corollaries to the first and second propositions of the 
Principia already noticed (§§ 13, 16). 
27. As regards the last of these, and the restoration of the 
plenum, I will only further observe (vide § 16), that even were 
* Current Phys. Ast ., b. iii., in loc. 
t Current Phys. Ast., § 54, ct passim ; also Append., in loc , 
