Let me call the reader's special attention to one or two statements of Herschel's given in this extract, in order to see how these statements harmonize with the view of the Aether submitted in this work. In the first place he states its shape is that of a lenticularly-formed envelope surrounding the sun, and extending beyond the orbits of Mercury and Venus, and probably to our earth. This harmonizes with the shape of the aetherial envelope as given in Art. 70. Then Herschel states it may be the denser part of that medium which we have reason to believe resists the motions of comets. That is exactly what it is, though Herschel failed to show why it should be the denser part of the Aether, as we have seen is the case, on account of its being gravitative. I will also prove later on, that Herschel was right with regard to the resistance of the motion of comets through it. Then he refers to its particles probably possessing inertia, as though he had anticipated the atomicity of the Aether, and assuming that atomicity, he was compelled to postulate inertia also as we have done in Art. 48. Lastly, he points out that each separate particle must have its own plane of motion, its own orbit, and its periodic time. Now this view fully coincides with that laid down in this article, where we have learned that the rotating Aether has its own plane of motion, that plane being the Plane of the Ecliptic, and as every particle or atom has its allotted place in the rotating Aether, then, as Herschel points out, the particle must have its own orbit, and plane of motion, and also its own periodic time. If, therefore, we had desired fuller confirmation of this atomic gravitating Aether, we could not have wished for more conclusive proof than that given by one of the greatest philosophical astronomers of the last century. We shall see later that Herschel also had a clearer view of cometary phenomena, and of the forces which played a part in those phenomena, than any of his contemporaries, when we deal with the origin and motions of all comets. Thus from Herschel we learn that the zodiacal light is caused by the atomic, gravitating, and rotatory Aether as that aetherial medium revolves round the sun, while at the same time every atom of the medium is itself in a state of rotation on its axis, as it performs its journey in its own orbit and in its own plane of motion. ART. 110. _Centripetal Force._--We have now to consider what is the physical cause of that part of the compound Law of Gravitation known as the Centripetal Force. As we have already learned (Art. 10), this force is really none other than the Attractive Force of Gravitation, in that its mode of operation always acts towards the centre of the attracting body, and hence was called by Newton the Centripetal Force.