Young, Charles A. (Charles Augustus), 1834-1908, Young, Anne Sewell, b. 1871., ed · Boston, New York [etc.] Ginn and Company · leaf 433
rom four to six inches indiameter) divided along its diameter, as shown in Fig. 150.The semi-lenses are so mounted that they can slide past eachother for a distance of three or four inches, the distance beingaccurately measured by a delicate scale, which is read by along microscope that comes down… … 414 APPENDIX. [$543 When the two halves of the object-glass are so placed thattheir optical centres, 0 and 1 or 0 and 2, coincide, they act as asingle lens, and form but a single image for each object in thefield of view: but as soon as they are separated, each half-lensforms its own image. The…
Astronomy · Constellations
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