Brewster, David, Sir, 1781-1868, Bache, A. D. (Alexander Dallas), 1806-1867 · Philadelphia : Lea and Blanchard · leaf 179
place of returning and encircling each pole A and B, encir-cle the two poles as an ellipse does its two foci. When we diminish the thickness of the plate of nitre, therings enlarge; the fifth ring will then surround both poles.At a less thickness, the fourth ring will surround them, till atlast all…
Optics
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