24.(Pg. [184]) How are the rays refracted by a concave lens, [fig. 7, plate 19]?
25.(Pg. [185]) What is the effect of one plane side in a lens?
26.(Pg. [185]) How is the focus of the plano-convex lens situated, [fig. 2, plate 20]?
27.(Pg. [185]) How does a convex lens magnify objects, [fig. 6, plate 19]?
28.(Pg. [185]) What is the article denominated which is represented at [fig. 3, plate 20]?
29.(Pg. [185]) How will a ray be refracted, which enters on one side of the prism, in the direction A B?
30.(Pg. [185]) What effect is produced by this refraction, as represented in [fig. 4, plate 20]?
31.(Pg. [186]) Of what are the rays of white light said to be composed?
32.(Pg. [186]) What colours are produced?
33.(Pg. [186]) By what property, in light, does refraction enable us to separate these different rays?