68 GREAT MEN OF SCIENCE 



investigator of nature, who not merely struck out in certain 

 directions and made progress of decisive importance, but 

 took hold of everything that he met with, tested it, and 

 strove to make it the means of discovering something new. 

 Since possibilities of this kind were increasing at that 

 time in number, it is not possible to discuss his work here 

 in all its many sided aspects; but we will first state in 

 general terms his chief contributions to the development of 

 knowledge. 



Galileo had taught us to understand the simplest pheno- 

 mena of motion; starting from them, Huygens provided 

 everything essential for carrying our understanding forward 

 for the most complicated processes, inasmuch as he investi- 

 gated certain complicated examples almost exhaustively, in 

 particular the compound pendulum, forced motion in a circle 

 with centrifugal force, and the phenomena of collision. He 

 was further the founder of our insight into the wave nature 

 of light, and the inventor and perfector of pendulum clocks; 

 and he also investigated thoroughly important parts of geo- 

 metry, particularly the properties of curves, such as the 

 cycloid.^ 



His personal character is shown in his work, and appears 

 also in all that is otherwise known of him; 'He shares with 

 Galileo a noble, unsurpassable, and complete uprightness. 

 He is quite open in stating the way by which he has been 

 led to his discoveries, and thus introduces the reader to a 

 full understanding of his achievement. He had also no 

 reason to conceal this way. Though we shall see after a 

 thousand years that he was a human being, we shall at the 

 same time observe what manner of man he was.'^ 



The activity of the investigator of nature is compared by 



* This is the line which a point on the circumference of a rolling wheel 

 traces upon a plane fixed with respect to the ground line along which the 

 wheel rolls. 



2 E. Mach, The Science of Mechanics, trans, by T. J. McCormack 

 (4th Ed. 19 1 9). 



