PRIMARY INDUCTION OF OPTICS. 375 



tharchus, who had been instructed by Eschylus in 

 the art of making decorations for the theatre, was 

 the first author on this subject, and Anaxagoras, 

 who was a pupil of Agatharchus, also wrote an 

 Actinographia, or doctrine of drawing by rays: 

 but none of these treatises are come down to us. 

 The moderns re-invented the art in the flourishing 

 times of their painting, that is, about the end of 

 the fifteenth century ; and, belonging to that period 

 also, we have treatises 2 upon it. 



But these are only deductive applications of the 

 most elementary optical doctrines; we must pro- 

 ceed to the inductions by which further discoveries 

 were made. 



2 Gauricus, 1504. 



