February 11, 1921] 



SCIENCE 



139 



those who pass them along. A good story 

 should never be spoiled by that. 



Jonathan Wright 

 Pleasantville, New York, 

 January 18, 1921 



REPLY TO PROFESSOR HORN 



Many times has the undersigned been 

 found to be in error on historical questions. 

 It is not easy to write during a period of 

 over thirty years without occasionally com- 

 mitting mistakes. Even Newton once said, 

 " It's impossible to print the book without 

 faults." However, it is due to myself to state 

 that not all the errors attributed to me are 

 errors in reality. In not a few cases the 

 critics themselves are in error. But never, 

 before the appearance of Professor D. W. 

 Horn's letter (Science, January 14, 1921), 

 have I been accused of " Eomancing in Sci- 

 ence." Had Professor Horn been less excited 

 and more contemplative, he would have writ- 

 ten differently. My account of Galileo was pre- 

 pared a quarter of a century ago. Were I to 

 re-write it, I would make some slight changes. 

 " Prior to Galileo it did not occur to any 

 one actually to try the experiment" relating to 

 acceleration. More recent research reveals 

 that Galileo, like most great scientific men, 

 had his forerunners. I say that Galileo pub- 

 licly experimented " one morning." This may 

 have been the correct time of day, but I am 

 not now able to verify the statement. Galileo 

 " allowed a one pound shot and a one hundred 

 pound shot to fall together." From Galileo's 

 " Dialogues Concerning two New Sciences " 

 it appears that he did perform this experi- 

 ment, but I am not sure that these were the 

 particular weights used when experimenting 

 before the university assembly. I have gone 

 over sentence by sentence the passage quoted 

 by Professor Horn and the above are the only 

 changes which seem to me perhaps necessary. 

 I repel as unjust the charge that I am 

 " romancing in science." 



Dr. Partridge rendered a service in calling 

 attention to Galileo's experiments at the 

 Tower of Pisa. However, I still think that 

 the Doctor overstated his case, was wrong in 



implying that Galileo made only one experi- 

 ment, and without sufficient reason called in 

 question the accuracy of Viviani's " Life of 

 Galileo " — a life which Favaro, after very 

 many years devoted to the study of Galileo, 

 has found to be remarkably reliable. Of 

 course, part of the discussion hinges on the 

 word " exactly." No description of an experi- 

 ment can be exact in every detail. However, 

 if essentials suffice, then our knowledge of 

 Galileo's experiments on falling bodies is 

 exact, for we know exactly the purpose of the 

 experiments, as well as the mode of experi- 

 mentation, namely, the dropping of different 

 weights of a variety of materials — mention 

 being made of some of the materials dropped. 



Professor Horn quotes: Fortis imagirMtio 

 generat causum. 1 agree, but whose casus is 

 it really? Florian Cajori 



University of California 



a correction 



To THE Editor of Science: The times are 

 actually worse than I realized when writing 

 recently about " Eomancing in Science." The 

 opening quotation should have read " tem- 

 pera," instead of " O tempus." The peculiar 

 appropriateness of this quotation is apparent, 

 for the correction came to me (from New 

 York) as part of an anonymous letter! 



David Wilbur Horn 



Bryn Mawr, Pennsylvania 



memoir of g. k. gilbert 



The undersigned is engaged in the prepara- 

 ration of a memoir of the late G. K. Gilbert, 

 to be published by the National Academy of 

 Sciences, and would be obliged if geologists 

 and others who possess letters from him or 

 who recall incidents that throw light upon 

 his character would submit them for incor- 

 poration in the story of his life. His great 

 contributions to geological science are pub- 

 lished and fully accessible; but the smaller 

 non-scientific matters which give the life of 

 a man its finer savor can be learned only by 

 personal commmiication from his friends. A 

 good number of such communications have 

 been already received; they are of so great 



