The modern Astronomers having, in a great measure, proved that the Stars are, in all respects, vast Globes of Fire like our Sun. Let us suppose a new-created Mind, or thinking Being, in a profound State of Ignorance, with regard to the Nature of all external Objects, but fully endowed with every human Sense and Force of Reason, suspended in Æther, exactly in the midway, betwixt [T]_Syrius_ and the Sun; in which Case, both of these Luminaries would equally appear much about the Brightness of the largest of our Planets. Now should such a Being, determined either by Accident or Choice, arrive at this our System of the Sun, and seeing all the planetary Bodies moving round him, I would ask you what you think he would imagine to be round _Syrius_? Your Answer, I think I may venture to say, would not be _nothing_; and methinks I already hear you say, Why Planets such as ours. [Footnote T: A Star of the first Magnitude in the greater _Dog_, and the most neighbouring to our Sun.] 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.