Collins, A. Frederick (Archie Frederick), 1869- · New York, London, D. Appleton and company · leaf 161
£ , : 6~ 5% try … HEAVY PASTE BOARD THIN CARDBOARD Fig. 153.—Pasteboard Mounting of Lens. Get two pasteboard tubes of the kind described for thepinhole telescope; the bore, or hole, of the first tube should be1% inches in diameter and it should be 2 inches long. Havethe second tube a little smaller than 1% inches in…
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