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If L L be a double convex-lens, and R R R parallel rays of white light, composed of the seven colored rays, each having a different index of refraction, they cannot be refracted to one and the same point; the red rays, being the least refrangible, will be bent to r, and the violet rays, being the most refrangible, to v: the distance v r constitutes the chromatic aberration, and the circle, of which the diameter is a l, the place or point of mean refraction, and is called the circle of least aberration.
As large as the life! cried I, in admiration 'I see the puppets, the wheelbarrows, every thing as large as life! "Mr. Y then told me, that it was by his grandson's directions that this glass, which he said was called a magnifying-glass, or convex-lens, was added to my show-box.
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