"Plano-" Quotes from Famous Books
 ... of spectacles is gathered from the writings of Roger Bacon, who died in 1292.[3] Bacon says: "This instrument (a plano-convex glass or large segment of a sphere) is useful to old men and to those who have weak eyes, for they may see the smallest letters ...
— Scientific American Supplement No. 822 - Volume XXXII, Number 822. Issue Date October 3, 1891 • Various
... Procure a plano-convex or a bi-convex 6-in. lens with a focal length of from 15 to 20 in. and a projecting lens 2 in. in diameter with such a focal length that will give a picture of the required size, or a lens of 12-in. ...
— The Boy Mechanic: Volume 1 - 700 Things For Boys To Do • Popular Mechanics
... lamp, giving a strong beam of light and heat, and with a plano-convex lens gather it into a single beam and direct it upon a thermometer, twenty feet away, that is made of glass and filled with air. The [Page 32] expansion or contraction of this air will indicate the varying amounts of heat. Watch your air-thermometer, on which ...
— Recreations in Astronomy - With Directions for Practical Experiments and Telescopic Work • Henry Warren |
