How? or, Spare hours made profitable for boys and girls (1887)
Holbrook, Kennedy · New York, Worthington co. · leaf 227
ll face in any direction,while by drawing the wire, e, it can be turned so as to re- 222 A BOYS SOLAR MICROSCOPE. fleet the suns rays through the lens, a, from whateverquarter of the heavens it may be shining. This doubleadjustment of the mirror and lens enables you to throwthe rays of the sun… … Fiy-5 The lens, a, should be held in place by two pieces ofwhalebone, bent around on either side of it, at the edgeof the opening in d; this lens is four inches in diameter,and has a focal length of nine or ten inches; its adjust-ment had better be left till everything else in the micro- A BOYS…
Handicraft · Amusements
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