52 SCIENCE OF THE MIDDLE AGES. PT. IT. 



tions, and that he explained the rainbow by saying that the 

 sun's rays are refracted or bent back by the falling drops 

 of rain, as was also noticed about the same time by Vitellio, 

 a Polish philosopher. 



Bacon is famous as the first man in Europe who made 

 gunpowder ; we do not know whether he learnt the method 

 from the Arabs, but it is most likely, for he gives the same 

 receipt for making it as Marcus Graecus did namely, salt- 

 petre, charcoal, and sulphur. He also knew that there are 

 different kinds of gas, or air as he calls it, and he tells us 

 that one of these puts out a flame. He invented the 

 schoolboy's favourite experiment of burning a candle under 

 a bell-glass to prove that when the air is used up the 

 candle goes out. 



Bacon seems also to have known the theory of a tele- 

 scope. We do not know whether he ever made one, but 

 he certainly understood how valuable it would be. -This 

 is what he says about it in his ' Opus Majus,' or * Greater 

 Work ' : ' We can place transparent bodies (that is, glasses) 

 in such a form and position between our eyes and other 

 objects that the rays shall be refracted and bent towards 

 any place we please, so that we shall see the object near at 

 hand, or at a distance, under any angle we please ; and 

 thus from an incredible distance we may read the smallest 

 letter, and may number the smallest particles of sand, by 

 reason of the greatness of the angle under which they 

 appear.' This is at least a very fair description of the tele- 

 scope and of the microscope. In the same book he says 

 that one day ships will go on the water without sails, and 

 carriages run on the roads without horses, and that people 

 will make machines to fly in the air. This shows that he 

 must have had some knowledge of many things which were 

 not really discovered till more than 300 years afterwards ; 



