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A Compendious and Methodical Account of the Principles of Natural Philosophy; As Explained and Illustrated in the Course of Experiments, Performed at the Academy in Little Tower-Street - Softcover
Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1730. Excerpt: ... Wherefore also the Dimensions of the Spectrum may be increased to any Magnitude, by increasing its distance from the Center of the Glass: For as the Distance of the Object from the Center of the Glass is to the distance of the Spectrum from the fame Center, so is the Height of the Object to the Height of the Spectrum. The Brightness of the Spectrum decreases as its Magnitude increases, because the fame Quantity of Light is expanded into a larger Space. The Aereal Spectrum may be rendered visible, either by receiving it upon a Sheet of Paper at the focal Distance, or by placing the Eye behind the Spectrum. If the Eye be placed between the Siectrum and the Glass, the Spectrum will appear double and not inverted: It appears double, because it is impossible to direct the Sight towards an Object that is behind us; and it appears in its true Position, because the Rays proceed immediately from the Object itself, and not from an inverted Spectrum. The apparent Magnitude of the Spectrum,-whether it be seen erect or inverted, depends upon the Distance of the Spectrum and the Center of the Eye. Let AB be a Convex-Glass Lens, p its Center, / its principal Focus, R a radiant Point placed, placed between the Glass and the principal Focus. All the Rays flowing from the Point R ihall be refracted by the Lens into Rays diverging from a certain virtual radiant Point, as /, on the fame fide of the Glass, with the Point R, but farther distant. As R approaches towards/", the distance/R decreases; but as R approaches towards F, the Distance / R increases. The Distance/may be found by the following Proportion; as RF to Fp, so is Rp to p/% or as R F to R p, so is Rp to R/. Wherefore, to an Eye placed on the other side of the Lens, the Point R shall appear in/. Here we may see th...
"synopsis" may belong to another edition of this title.
- PublisherGeneral Books LLC
- Publication date2012
- ISBN 10 1150023252
- ISBN 13 9781150023255
- BindingPaperback
- LanguageEnglish
- Number of pages46
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