Light visible and invisible : a series of lectures delivered at the Royal Institution of Great Britain, at Christmas, 1896 (1897)
Thompson, Silvanus Phillips, 1851-1916, Royal Institution of Great Britain · New York : Macmillan · leaf 57
Fit;. 23. 4o LIGHT LECT. though it is of a bent and crooked shape, the lighttravels until it comes to the other end. Returning now to the use of lenses to cause thewaves to converge and diverge, we will adjust our lan-tern to send out a straight beam, and then interpose in … Fig. 24. the path a lens made of glass thicker in the middlethan at the edges. At once it is observed—thanks tothe dust in the air—to make these waves converge to afocus at F (Fig. 25). This is again a real focus. A lensthat is thus thicker in the middle than at the edges iscalled a convex lens.…
Light · X-rays
Internet Archive · UBC Library · Public Domain Mark 1.0. Free to use for anything.
