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SCIENCE 



[N. S. Vol. XXXVII, No. 952 



of two of his students, led to the invention 

 of the barometer, and, in the hands of von 

 Guericke, to the air pump. Torricelli 

 knew well the Dialogues on Motion. 



6. Finally, Galileo was an inspiring 

 teacher and built up at Padua a great 

 school of physics. Many of his students 

 lodged under his own roof; helped him in 

 his own garden ; ate at his own table. He 

 had his own workshop and employed his 

 own mechanicians. Generous with his 

 time, his energy and his money, master of 

 a fine literary style, endowed with a keen 

 sense of humor, familiar with the best that 

 had been said and thought in the world, 

 standing in the front rank of investigators, 

 is it any wonder that young men of talent 

 hastened to Padua from all parts of 

 Europe? Could any higher compliment 

 be paid to a teacher than the devotion 

 exhibited by the youthful Viviani, a lad 

 in his teens, for his master already some 

 seventy years old and a "Prisoner in 

 Acetri"? If deferred payments of the 

 kind that teachers mostly depend upon 

 ever get as far as the next world, surely 

 this courageous spirit, harried throughout 

 his long life by poverty, ill-health and the 

 censorship of the church, must have been 

 gratified by the work of the Accademia del 

 Gimento which was, with the exception of 

 a single man, composed entirely of his 

 students. Mechanics was the one subject 

 to which he was devoted consistently and 

 persistently throughout his life; it was the 

 subject of his earliest investigation when a 

 young man at Pisa ; the subject upon which 

 he lectured when in his prime at Padua; 

 the subject of his latest and most mature 

 reflection at Arcetri. His most important 

 contribution to dynamics was published in 

 the seventy-third year of his age. 



If, in conclusion, I were asked to sum- 

 marize in a single sentence the principal 

 contributions of Galileo to the science of 



physics, I should mention the two follow- 

 ing facts: (1) That knowledge of physical 

 phenomena which is to receive "imper- 

 sonal 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 impor- 

 tant 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 experiment 

 can rob a man of all arrogance of opinion, 

 how familiarity with unsolved problems 

 can give a man genuine humility, and how, 

 on the other hand, the possession of clear 

 experimental evidence arms him with sure 

 confidence. 



Critics tell us that Florence, during the 

 Renaissance, shone with a borrowed light 

 — a light reflected from Athens. But I 

 venture to think that those who will take 

 the pains to look over the pages of Galileo 

 will find them self-luminous. 



Heney Crew 



Northwestern University 



FACTS AND FICTION ABOUT CBOPS 

 The Association of Official Agricultural 

 Chemists of the United States at the Norfolk 

 meeting, in 1907, unanimously adopted a com- 

 miteee report' endorsing the following dec- 

 laration : 



It is as truly the duty of science to protect 

 agriculture from error as it is to afford new truth, 



^See Circular No. 123 of the University of 

 Illinois Agricultural Experiment Station. 



