415 
tions, the result, if there be no deflecting force, must be a growing 
divergence, and a motion becoming more and more obtuse to the 
new line of junction. A force tending towards the other body will 
be required, to hinder this divergence, and transform the momentary 
lateral into a permanently circular or elliptical motion. But all 
tins is clearly relative. It involves the relation of one body to the 
other, and of both to their centre of gravity. Any number of 
bodies in one plane, at the corners of a regular polygon, niio-ht thus 
revolve in their own plane with a circular motion. There would 
need only a definite relation between the angular velocity and the 
central force, or deflecting power. But if all moved also in parallel 
directions, towards some distant body with a common velocity, the 
hist relative motions would be unaffected, and the circularity re- 
tained. Thus any additional absolute motion, common to all the 
bodies, could not affect their relative motions, or the amount of 
foicc needed to counteract a tangential divergence. The second 
method, then, must fail, no less than the first, to bridge over the 
impassable gulf between relative and so-called absolute motions. 
.36. The result of these reasonings may be summed up, I con- 
ceive, in the following axioms : — 
1. All the motions, of which we have or can have any ex- 
perience, are relative motions only. 
2. Relative motions might be turned into absolute, if the abso- 
lute motion of any one body with reference to mere empty space, 
could be ascertained. But this discovery is impossible. 
3. Absolute motions are thus a mental illusion, and nothin " 
more. . We first invent or mentally conceive an immense number 
of points,, having fixed place-relations to each other, and then, 
still conceiving these as without motion, think of known visible 
bodies as moving with reference to them. 
4. Real motion is a change of place with reference to really 
existing bodies. J 
.5. Imaginary motion is a change of place with reference to 
points or bodies only conceived to exist. 
6. The language of relative motion is equally true, and scienti- 
fically faultless, whatever plane of vision or point of smht we assume 
to which the changes are referred. 
37. These axioms, if true, will help to clear away a mist 
which has rested on this whole subject from the time of Copernicus 
down, to the present day. The remarks in the Fifth Essay are 
one signal example of an error and misconception, which has very 
widely prevailed. Professing to be wiser than common speech and 
the language of the Bible, Modern Science has overleapt the bounds 
of truth, and become guilty of unscientific error. This same 
error, which imputes inaccuracy and falsehood, not only to the lan- 
guage of Scripture, but to the daily speech of all mankind, has 
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