Johnson's natural philosophy and key to philosophical charts : illustrated with 500 cuts; being reduced photographic copies of all the diagrams contained in the author's philosophical series of indestructible school charts ; for the use of schools and families (1878)
ike clock-work, is made to revolve. By this means an observerat any point will see eight flashes of light during one revolution, whichare followed by as many intervals of darkness, called eclijjses. One light-house is distinguished from another by varying therevolutions of the lights. Concave… … rays, more divergent. The divergent rays from the radiant L, by pass-ing through the double concave lens, are rendered more divergent, andtake the directions of M and N, as though proceeding from a pointbehind the lens, as shown by the dotted lines. This point is called thevirtual focus. 236…
Physics · Astronomy
Internet Archive · University of Connecticut Library · Public Domain Mark 1.0. Free to use for anything.
