[Sidenote: _Improbability_ of a concave Appearance of the Clouds and Earth, _lessened_, by a familiar Illustration.] 50. Some may find a Difficulty in conceiving, how the whole Prospect of Clouds and Earth together coud put on a _concave_ Appearance: both of which were in Reality _convex_, with Respect to the Situation of the Observer in the Car. A familiar Illustration may help to remove the Objection. Imagine a Person placed in the Center of a Plain, or Carpet; extended every Way beyond the Reach of the Eye. If in that Situation he was gradually elevated; the _distant_ Parts of the Carpet woud _seem_ to rise with him: and those Figures of the Pattern woud alone be distinguished, that lay immediately below the Eye: the more remote becoming dim and faint. The whole would put on the Form of a concave Bowl; as soon as he had risen to so great a Height, as plainly to perceive the Figures of the surrounding Pattern more and more foreshortened, in Proportion to their Distance from the Center of the Carpet. CHAPTER VIII. Section 51. The Perspective of the Clouds was entirely new; and remarkable both for Beauty and Grandeur. The lowest Bed of Vapour that _first_ put on the Appearance of Cloud was of _a pure white_; in detached Fleeces; encreasing as they rose. They presently coalesced, and were aggrandized into +a Sea+ _of Cotton_, but more _white_; and _dazling_: tufted here and there by the light Play of Air, and gentle Breezes in every Direction: but where undisturbed, the Whole became an extended Firmament or _white_ Floor of thin Cloud, thro’ whose Intervals the Sun must shine with fiercer Gleam. The upper Surface was quite even: not blended with the Air above, but defined and separated with the utmost Exactness; being condensed by the Coolness, and checked in their Ascent, by the Levity of the superior Regions. Thro’ this _white_ Floor uprose in splendid Majesty and awful Grandeur, at great and unequal Distances, a vast Assemblage of _Thunder-Clouds_: each Congeries consisting of whole Acres in the densest Form. [Sidenote: Circular Boundary of the _celestial_ Prospect from the Balloon _above_ the clouds.] 52. Their conglomerate and fringed Tops rising, at different Distances, in circular Order, one above the other, to the Number of _thirty_: till they became imperceptible from their remote Situation: the Eye commanding an Extent of 102 Miles.[18] Their Form was, as if Pieces of Ordnance were discharged perpendicularly upwards into the Air: and that the Smoke had consolidated, at the Instant of Explosion, into Masses of Snow or Hail: had penetrated thro’ the upper Surface or _white_ Floor of common Clouds, and there remained visible, and at Rest.