Collins, A. Frederick (Archie Frederick), 1869- · New York, London, D. Appleton and company · leaf 162
ort. A lens of thiskind can be bought for 25 or 30 cents.The smaller lens for the eyepiece is adouble concave lens 1 inch in diameter andhaving a focus of 2 inches. This lens canbe had for about 40 cents. Cut a strip of thin, tough cardboard % inch wide and 6inches long; on this strip glue a strip… … Fig 154. — Paste-board Lens Mount-ing. OUTSIDE PASTEBOARD _*TUBE MOUNTING INSIDE TUBE
Astronomy · Stars
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
![An illustration from [Electric engineering.] (1902)](https://img.insideoutlibrary.com/img/200/ia-electricengineer02inte-423-243.webp)
