in 



logue of Zeuxis, speaks of the effects of perspective in 

 pictures. Philostratus, in his preface to his drawings^ 

 or history of painting, makes it appear that he kne>V 

 this science ; and in the description he gives of Mena. 

 tius's picture of the siege of Thebes, he places full in 

 sight the happy effects of perspective when studied with 

 care. There he extols the genius of this painter, who, 

 in representing the walls of the place invested and 

 scaled by soldiers, placed some of them full in view, 

 others to be seen only as far as the knee, others only 

 at half length, and others whose heads only, or hel- 

 mets, were seen, till the whole ended in the points of 

 the spears of those who .were not seen at all: and he 

 adds, that aH this was the effect of perspective, which 

 deceives the eye by means of the flexure of its lines, 

 which gradually approaching one another as they seem 

 to recede from vi?Wj proportionally diminish the en- 

 closed objects, and make them appear to retire. 



8. Aristotle was the first who proposed the famous 

 problem respecting the roundness of that image of the 

 sun, which is formed by his rays passing through a 

 small puncture, even though the hole itself be square 

 or triangular. Marolle, resolved this about the mid. 

 die of the fifteenth century, by demonstrating that 

 this puncture is the vertex of two cones of light, the 

 one of which has the sun itself for its base, and the 

 other the refracted tniagc. Upon this M. de Montncla 

 ascribes to hi-m (he whole honour of the solution of this 

 optical problem, formerly indeed proposed by Ari- 

 stotle, but which that ancient philosopher, says he, 

 according to his wonted way, had but badly accounted 

 for. It is with regret that I find myself obliged to 

 animadvert upon some very material mistakes into 

 which At. de Mofttucla has slipped, whose judgment I so 

 much revere on other occasions. For first of all, from 

 his manner of quoting this problem of Aristotle, it ap- 

 pears that he neither consulted the Greek texi, nor 

 even the Latin version that accompanies it : insomuch 

 that 1 am quite at a loss to conceive wiiere lie came by 



