Containing the Economy of Vegetation

Containing the Economy of Vegetation

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1795 edition. Excerpt: pass on and tinge the morning and evening clouds with their colours. See Priestleyk History of Light and Colours, p. 440. But as the particles of air, like those of water, are themselves blue, a blue shadow may be seen at all times of the day, though much more beautifully in the mornings and evenings, or by means of a candle in the middle of the day. For if a shadow on a piece of white paper is produced by placing your finger between the paper and a candle in the day light, the shadow will appear very blue; the yellow light of the candle upon the other parts of the paper apparently deepens the blue by its contrast, these colours being opposite to each other, as explained in note II. Colours are produced from clouds or mists by refraction, as well as by reflection. In riding in the night over an unequal countryI observed a very beautiful coloured halo round the moon, whenever I was covered with a few feet of mist, as I ascended from the vallies; which ceased to appear when I rose above the mist. This I suppose was owing to the thinness of the stratum of mist, in which I was immersed; had it been thicker, the colours refracted by the small drops, of which a fog consists, would not have passed through it down to my eye. _ There isa bright spot seen on the cornea of the eye, when we face awindow, which is much attended to by portrait painters; this is the light reflected from the spherical surface of the polished cornea, and brought to a focus; if the observer is placed in this focus, he fees the image of the window; if he is placed before or behind the focus, he only fees a luminous spot, which is more luminous and of less extent, the nearer he approaches to the focus. The lumin ous appearance of the eyes of animals in the dusky more

Product details

  • Paperback | 60 pages
  • 189 x 246 x 3mm | 127g
  • United States
  • English
  • black & white illustrations
  • 1236873270
  • 9781236873279