74 SIXTEENTH CENTURY. PT. in. 



for making accurate drawings of objects ; for, by tracing out 

 with colours on the wall the figure of the man or tree as it 

 stood, he could get a small image of it with all its propor- 

 tions and colours correct. But, what is still more important, 

 he was led by this experiment to understand how we see 

 objects, and to prove that Alhazen was right in saying that 

 rays of light from the things around us strike upon our eye. 

 For, said Porta, the little hole in the shutter with the lens 

 in it is like the little hole in our eye, which also contains a 

 natural convex lens ; and we see objects clearly because the 

 rays pass through this small hole. He did not, however, 

 know which part of our eye represents the wall on which the 

 figure is thrown, nor why we see objects upright ; we shall 

 see (p. 94) that Kepler discovered this many years afterwards. 



When Porta had succeeded in getting clear images of 

 real things on the wall, he began to try painting artificial 

 pictures on thin transparent paper and passing them across 

 the hole in the shutter, and he found that the sun threw a 

 very fair picture of them on the wall In this way he pro- 

 duced representations of battles and hunts, and so made a 

 step towards the Magic Lantern. He seems, however, never 

 to have tried it by lamplight ; this was done by Kircher, a 

 German, about fifty years later. There is no doubt that 

 Porta had a very good notion of how to use two magnifying 

 glasses so as to make objects appear nearer and larger, but 

 it is not certain that he ever really made a telescope. 



Dr. Gilbert, the Founder of the Science of Elec- 

 tricity, 1540-1603. It was about this time, while Baptiste 

 Porta was making experiments on light in Italy, that an 

 Englishman named Gilbert made the first step in one of the 

 most wonderful and interesting of all the sciences, namely, 

 that of Electricity. So long ago as the time of the Greeks 

 it was already known that amber, when rubbed, will attract 



