THE MICROSCOPE. 37 



ment of a sphere and of a whole sphere, and lays claim to being the 

 first to notice the refraction of rays into it.' 



Vitellio, a native of Poland, followed Alhazen by publishing a 

 work illustrative of his predecessor in 1270. His work contained 

 all that was valuable in Alhazen's, and much that was new. He 

 makes mention of the fact that light is lost by refraction and reflec- 

 tion, and that as a consequence bodies viewed by lenses appear less 

 luminous. 



Ten years later there is added to the stock of books, but not of 

 knowledge a work from the pen of the Archbishop of Canterbury, 

 Peccani. 



Roger Bacon, a Monk, writing at same time, also fails to add 

 to our meagre stock of information. Reasoning from some of Alha- 

 zen's statements, of whom he was a close student, he deducted as 

 -follows: "When an object is placed nearer to the eye than the cen- 

 ter of sphere of which the interposed glass is a lesser segment and 

 the convex side toward the eye, everything concurs to magnify it. 

 For, the angle under which it is seen is greater, the image larger 

 and place of the image nearer. Therefore, this instrument is use- 

 ful to old people and those who have weak eyes; for by the help of 

 it they may see the smallest letters sufficiently large."* It is sup- 

 posed that the statement, plus Alhazen's remarks, were the imme- 

 diate forerunner of spectacles. At all events it is certain that 

 specs came into use about this time. 



Bacon further says (Opus Majus), deducting from theory of re- 

 fraction that it was possible by means similar to those used to see 

 small near objects, to see distant ones. This we must acknowledge 

 was a near approach to the theory of both microscope and telescope. 

 I say theory, for it becomes evident from many after statements 

 that he knew nothing of the result of "certain combinations of 

 lenses " practically. Then, too, he never refers to any tests of his 

 theories, which he undoubtedly would, had he made any. How 

 much we have lost in time and results by the lack of practical 

 knowledge on the part of this great genius we can only surmise. 



Before going into the next and brighter era, I want to finish 

 with spectacles. As stated, they were in use during the thirteenth 

 century and not long before. In proof of this we have accounts of 



' Smith's Optics 



2 Opus Maj., p. 352. 



