400 
already alluded to (§ 31), prepared for the Bath Meeting of 
the British Association, and rejected;* in which I also show 
that if the sun does affect the moon’s real motions upon the 
heliocentric hypothesis, its influence is repulsive , or the very 
reverse of what appears to be proved by all the fallacious 
demonstrations that deal with the moon’s relative or apparent 
motions only. 
33. There are still a few points connected with current 
physical astronomy to which I desire briefly to direct your 
attention. There are, especially, two dogmas of Newton’s 
Principia universally accepted as true, and constantly in men’s 
mouths, which I wish to bring before you, and ask you to 
consider, with the reasoning upon which they are based, in 
the ipsissima verba of Newton. One of these dogmas is em- 
bodied in what is called the Third Law of Motion, and it is as 
follows, viz. : — 
“ Law III.— To every action there is always opposed an equal reaction ; or , 
the mutual actions of two bodies upon each other are always equal, and directed 
to contrary parts” 
Such is <e the law,” as laid down in Newton’s “ immortal 
work ” ! — -Now, listen to the reasoning upon which this law is 
founded : — 
“ Whatever draws or presses another, is as much drawn or pressed by that 
other. If you press a stone with your finger, the finger is also pressed by the 
stone. If a horse draws a stone tied to a rope, the horse (if I may so speak) 
will be equally drawn back towards the stone.” {Prin., book i., sect. 1.) 
Now, in direct opposition to this, I have already ventured 
to assert, and beg leave now to repeat — 
“ That mere matter, and therefore all material bodies, can only be truly 
regarded as perfectly passive, and without any tendency or inclination of their 
own ; and that consequently it follows that whenever a body offers resistance 
to any action exerted upon it, or to any force impressed against it, such 
resistance is not due to the matter or body itself, or to any vis inertice, but 
to some previously impressed force or influence affecting the body. So, when 
a horse draws a stone tied to a rope on level ground, the resistance the horse 
has to overcome is due to the weight of the stone and the friction resulting 
therefrom. If the stone is small and light, the resistance may be so small as 
to be unfelt ; or the stone may be so large and heavy, that the horse can 
only with the greatest difficulty move it ; or it might be so heavy, that the 
horse could not move it at all ; in which case there would be no friction, and 
* Vide Note D. 
