221. The extreme Rarity or Tenuity of the Vapours was evident from the progressive Course of the Balloon, which was always in the Center of a circular Opening, limiting the lower Prospects; except when the Spectator lost all Sight of the Earth, by dense, watry, intervening Clouds.
Novel Situation peculiar to the Balloon, again described.
This august central Situation, always changing yet still the same, had the most striking Effect on the Senses and Imagination. Yet, however pleasing the Recollection of this glorious appearance; however strongly impressed, accurately described, or richly painted; it must fall infinitely short of the original sensation. Unity and Sameness were there contrasted with perpetual Variety: Beauty of Colouring; Minuteness, and consummate Arrangement;—with Magnificence and Splendor: actual Immensity;—with apparent Limitation:—all which were distinctly conveyed to the Mind, at the same Instant, throu’ the Intervention of the Organs of Sight: and, to complete the Scene, was added the Charm of novelty.
CHAPTER XXXIX.
CONJECTURES ON THE CAUSES OF THE CIRCULAR TRANSPARENCY TO A CERTAIN DISTANCE BELOW THE BALLOON, AND OF THE RED LIGHT FROM THE SEA AND RIVERS, WHEN SEEN ABOVE THE LEVEL OF THE SUPERIOR CLOUDS.
On the circular Transparency.
Section 222.QUERE: As Red is the heaviest and Blue the lightest Colour; and as red Rays blended at a certain Angle with blue Rays, produce Opacity: further; as red is the predominant Colour reflected from Water, while in the Form of dense Cloud, for Instance at the Rising and Setting of the Sun; and blue the Colour always reflected from the light Medium of Air or Sky; Does not this Mixture of least and most refrangible Rays, which, when aided with the intermediate primary ones, causes a Transparency near and round the Eye of a Spectator placed either on Earth or among the Clouds; produce, at a greater Distance and different Angle, such a Degree of Opacity, as actually to give the Idea of Clouds surrounding him at a Distance?
The latter Part at least is true, that Vapour and Air, which are naturally qualified to transmit red and blue, rather than any other Light, will, at a certain Angle, when blended, produce an opacity. (See the Letter sent by Newton from Cambridge to Dr. Derham, in order to be presented to the Royal Society,—in “Miscellanea Curiosa, Vol. 1, Page 109.”)
On the red Light from the Sea and Rivers.