PLATE XI.
Is designed as a geometrical Scale to all the primary Parts of the visible Creation, with regard to the Distance of Orbits compared with the Globe of the Sun; by which at once may be conceived, and justly measured in the Mind, not only the mean Distance of the Planets with regard to one another, but also that of the Comets, and even the comparative Distances of the nearest of the Stars, which will, I guess, greatly help you to form an Idea of the vast Extent of Space necessary to comprehend the whole Creation.
Fig. 1. Is a Radius of the Orbit of Mercury, in true Proportion to the Body of the Sun represented at S, shewing at the same time a small Portion of the opaque Planet's Orbit, and the real Length of its Shadow at P.
Fig. 2. Is a Radius of the whole System of the Planets as far as the Orbit of Saturn in Proportion to a compleat Orbit of Mercury, much less than the former; the former serving as a better known Scale to consider the amazing Distances of the more remote Planets by.
Lastly, Fig. 3. Is a Representation of the least possible Distance of Syrius and the Sun, proportionable to the Magnitude of the Sphere of our Comets, &c. represented at S, whereby it evidently appears, that as all the Planets of Syrius must be included within the small Sphere represented in the Center P, none of them could possibly be seen at the Sun, not only by reason of the Smallness of the Angle of Sustension, or Elongation, but also as being lost in the superior Light of Syrius himself, in so minute an Orb of Vicinity.
Consequently (as you must perceive) no Arguments can possibly be drawn to deny the Existence of such Bodies, with any Shew of Reason, from their not having been seen by us.
Here I must observe to you, that you cannot consider this Scale of Orbits too much before you look upon Plate XVII.
To conclude, it evidently seems to be the End and Design of Providence, by this visible Variety of Beings, to lift the Minds of Men above this narrow Earth, in Search of that powerful Being upon which we are all so much dependant; and the Creator, no doubt, in this vast Display of his Wisdom and Power, designed the amazing Whole, as the adequate Object of every Part, and as such equally open on all Sides, to the penetrating Progress of human Minds, and through the most extensive Faculty of Sense, the Sight, to draw our Reason and Understanding by Degrees, from finite Objects into Infinity; and as the last Result of celestial Contemplations place within our Reach, a certain Evidence of a future State, and the manifest Mansions of Rewards and Punishments, suited no doubt most equitably to all Degrees of Virtue, and to every Vice.
"When I consider (says Mr. Addison, speaking as having taken particular notice of a fine Evening) that infinite Host of Stars, or to speak more philosophically of Suns, which were then shining upon me, with those innumerable Sets of Planets or Worlds, which were then moving round their respective Suns; when I still enlarge the Idea, and supposed another Heaven of Suns and Worlds rising still above this which we discovered; and these still enlightened by a superior Firmament of Luminaries, which are planted at so great a Distance, that they may appear to the Inhabitants of the former as the Stars do to us; in short, whilst I pursued this Thought, I could not but reflect on that little insignificant Figure which I myself bore amongst the Immensity of God's Works:" This Reflection, I judge, as you are an Admirer of the Author, you will not look upon as impertinent in this Place, especially as it must enforce what I have endeavoured to shew you, namely, the Reasonableness of a Plurality of sidereal Systems, and their Multiplicity of Worlds; which, if you are yet in Doubt of, I hope you will at least forgive so well designed an Attempt with your usual Candour.
I am now prepared to proceed in the chief Design of this Undertaking, which is to solve the Phænomena of the Via Lactea; and propose in my next to answer more fully your farther Request.
I am, &c.
