ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 585 



eagerly bought up by some great folks, who placing them on the nose 

 of their unfortunate courtiers 8o alter the sight of the wretches that 

 they esteem the low favour of being slapped on the slioulder by the 

 master, or being looked at by him with a grin even artificial and forced, 

 worth the remuneration of an income of five hundred crowTis." 



Which passage reproduced in the 2nd edition of the same Collec- 

 tion, published in 1614: (' Ragguaglio primo,' p. 4, line 4 and following), 

 continues thus :— 



" But the occhiali lately invented in Flanders are bought at a high 

 price by these same personages and then made a present of to their 

 courtiers, which when usel by them make them see as very near them 

 those prizes and those dignities which are not within reach of their 

 sight, and which may never be within reach of their age." 



From this addition of Boccalini's one sees that in the first passage 

 the word occhiali is used for lenses and not telescopes as some believed, 

 through reading only the first edition of the book, since the telescope 

 is clearly indicated in the addition, it being called " occhiale lately 

 invented in Flanders." 



We may therefore conclude from what has been said that although 

 lenses for the enlargement of objects had been discovered, their use 

 was scarcely understood, and they were only used for base objects as 

 Alimberto Mam-i aflSrms, without any one thinking of using them to 

 increase our knowledge of the smaller details of large objects, or the 

 existence of very small objects undiscernible to the naked eye. 



Many strange ideas were mooted in those times concerning lenses 

 (and some have been seen in the preceding quotations), because all who 

 had made use of them had confused the enlargement of the ocular image 

 produced by the lens with the approach of the same image to the eye, 

 although these two things are comj^letely different. 



When an object is examined through a convex lens, and the enlarged 

 vii'tual image of the object is seen, instinct makes us believe it to be 

 very near, although at times it is really at an infinite distance, and the 

 eye adapts itself to look at it at that distance, as if it were looking 

 without the aid of a lens at an object at a great distance. This sensa- 

 tion (or rather this invincible feeling of a sensation, invincible even for 

 those who know quite well that converging lenses make us see the 

 object far more distant from the eye than it really is) springs from our 

 powerlessness to estimate distance at sight, especially in the case of 

 rather long distances and of things looked at with only one eye, if the 

 apparent size of the object does not help us to judge its distance better. 

 Now on looking through a converging lens the objects almost all appear 

 to us of the same size, whether their image is formed quite close to the 

 eye or at an enormous distance. (37) 



In this way, comparing through a lens a very large object with its 

 more minute details, which we know to be small, and not being able to 

 recognize the true place of its image, we believe it to be near, although 

 it is always further ofi" than the object from which it arises. 



The contrary happens with diverging lenses, which, producing on 

 the retina a smaller image than would be shown to the naked eye by the 

 object observed if it were placed at the same distance at which its image 

 is formed, we imagine the image to be very distant, whilst it really is 

 always nearer the eye than the object seen. 



This illusion concerning the real distance of images contemplated 



