THE PRESIDENT'S ADDRESS 33 



I should mention the two following- facts: (1) That knowl- 

 edge of physical phenomena which is to receive ''impersonal 

 verification" and become useful, must be obtained mainly by 

 experiment adapted to ask of nature some particular question. 

 (2) That momentum considered as a function of time and 

 position is a fundamental dynamical concept; or, in other 

 words, to discover how the change of momentum of any body 

 is connected with the physical circumstances in which the 

 body is placed, is the one great problem of dynamics. 



But perhaps, after all. his most important contributions 

 lie outside of physics. Indeed Galileo has not yet shot his last 

 arrow. For his life still teaches us that nothing is so because 

 any man says it is so. His example still shows how^ experi- 

 ment can rob a man of all arrogance of opinion, how familiar- 

 ity W'ith unsolved problems can give a man genuine humility, 

 and how\ on the other hand, the possession of clear experi- 

 mental evidence arms him with sure confidence. 



Critics tell us that Florence, during the Renaissance. 

 sh(^wn with a borrowed light — a light reflected from Athens. 

 But T venture to think that those who will take the pains to 

 look i:^ver the pages of Galileo will find them self-luminous. 



(1^ "Renaipsarce in Ita]y," Vol. I., p. 234. 



(2) Aocademia del Cimento, founded in 1657: disbanded in 1667. 



(3) Ed'ted by ti.e scholarly care of Professor Favaro. of the Uni- 

 versity of Padua, and published by the Italian government. 1890-1909. 

 Referred to hereafter as "Nat. Ed." 



(4) For a mastorlj presentation of this phase of Galileo's work, 

 .=;.;e Dr. Charles J. Little's article in the Methodist Review, Vol. 88, pp. 

 204-218. 1906. 



(5) Gothe, "Farben-lehre Historiche Theil." art. Galileo. 



(6) Mann, "Teaching of Physics." pp. 107-110 (Macmillan, 1912). 



(7) "Xat. Ed.," Vol. 5, pp. 326. Translated in Fahie's "Galileo." 

 p. 187. 



(8) "Nat. Ed.," Vol. 6, p. 340. Translated in Fahie's "Galileo," 



(9) Lasswitz. "Atomistick," Bd.2, pp. 14-'*3, gives a good descrip- 

 tion of Benedetti's work. 



(10) Huygens. "Horologium Oscillatorium," Part V., Prop. 13; or 

 Hobart, "School Science and Mathematics," Vol. 11, p. 692 (1911), for 

 translation of Huygens' paper. 



(11) Galileo. "Dialogues on Motion," Fourth Day, Problem I. et 

 seq. 



(12) "Nat. Ed.," Vol. II., p. 166. 



(13) Clifford, Nature, Vol. 22, p. 122 (1880). 



(14) Poincare, lecture before the Wissenschaftlich Verin in Ber- 

 lin, p. 116 (Teubner, 1912). 



(1.5) "Nat. Ed.," Vol. 8. pp. 128-130, First Day, translated into Ger- 

 man bv von Oettinger. Ostwad's Wiss. Klassiker, No. 11, p. 76. 

 (i6) "Greek Thinkers," Vol. 4, p. 108, Berry's translation. 



(17) First Day, "Nat. Ed.," Vol. 8, p. 78. 



(18) Third Day, "Nat. Ed.." Vol. 8, p. 191. 



(19) "Nat. Ed.," Vol. 8, p. 124, First Day. 



