THE PRESIDENT'S ADDRESS 25 



times, endured opposition, criticism, disgrace and social ostra- 

 cism tiiroughout most of his thinking life. I refer to Galileo. 

 But I shall speak only of what he did in physics, because 1 

 believe this phase of his work is too little known. 



What Galileo saw through telescopes of his own make, 

 though not of his own invention, is so familiar that possibly a 

 majority of intelligent men think of him mainly as an astrono- 

 mer. The spots on the sun. the mountains on the moon, the 

 satellites of Jupiter, the phases of \'enus. the ''triple charac- 

 ter" of Saturn, the solar rotation period, lunar libration and 

 earth-shine are some of the celestial phenomena associated 

 with the name of Galileo. These and his brilliant defense of 

 the Copernican system are responsible for the impression that 

 liis accomplishments are chiefly astronomical. 



To another large group of men he stands mainly for lib- 

 erty, intellectual, social and religious. These men classify 

 nim with Giordano Bruno and De Dominis and Campanella 

 who also had some experience with the cardinals of the In- 

 quisition. For them Galileo is the man who dared to differ 

 with Aristotle, the man who brushed aside the mists of phil- 

 osophy, the man who banished church traditions from his 

 thinking while he calmly pursued his search after unity in the 

 physical universe. (4) It is doubtless his splendid stand for 

 spiritual freedom which leads Goethe (5) in his historical 

 sketch of optics to say 



Even though he never seriously studied the sub- 

 ject of color. I must at least adorn my page with his 

 name. 



But there is still a third group of men to whom the great 

 Italian appeals most strongly because he has given them a new 

 method of working and thinking, a new viewpoint, a new 

 apercu. To put this contribution in its proper perspective is 

 not an easv matter: we are too near it and too familiar with 

 it. If. however, one considers the time interval between Archi- 

 medes and Kelvin he can not fail to notice a sharp discontinu- 

 ity in the progress of physics occurring about the beginning 

 of the seventeenth century. Just how commerce and industry 

 led up to. and prepared the way. for this step is the subject 

 of a most interest chapter by a member of this academy. Pro- 

 fessor Mann. (6) 



Without underestimating the contribution of Pappus or 

 Tartaglia or Benedetti of Stevinus or Leonardo da Vinci, to 

 mechanics ; and without denying the important role of statics 

 in architecture and in other structural work one may. I be- 

 lieve, fairly say that the years which intervene between Arch- 

 imed'es and Galileo are practically barren of progress ir 

 physics. 



