October 29, 1920] 



SCIENCE 



409 



GALILEO'S EXPERIMENTS FROM THE TOWER 

 OF PISA 



Mr. Partridge's declaration (Science, Sept. 

 17, 1920) that " we do not know exactly what 

 experiment Galileo performed " from the lean- 

 ing tower of Pisa appears to me too sweep- 

 ing. In the first place, Vincenzio Viviani, 

 in his life of Galileo, speaks of " repeated, 

 experiments " not of one " experiment." A 

 series of trials is what one would ex- 

 pect. It is highly improbable that Galileo 

 would perform an experiment before a uni- 

 versity assembly which he had not previously 

 tried out. The historic data are as follows: 



(1) Viviani tells us that Galileo at the lean- 

 ing tower of Pisa used " different weights " ; 



(2) Galileo in his " De Motu" (probably 

 written before he left Pisa) speaks of drop- 

 ping wood and lead from a high tower; (3) 

 In his " Dialogues concerning two new Sci- 

 ences,"^ Galileo lets Sagredo say: 



But I, Simplieio, who have made the test can as- 

 sure you that a eannon ball weighing one or two 

 hundred pounds, or even more, will not reach the 

 ground by as much as a span ahead of a musket 

 ball weighing onily half a pound, provided both are 

 dropped from a height of 200 cubits. 



Later Salviati says that "the larger (iron 

 ball) outstrips the smaller by two finger- 

 breadths." On the remark of Simplieio that 

 perhaps the result would be different if the 

 fall took place "from some thousands of 

 cubits," Salviati replies: 



If this were what Aristotle meant you would 

 burden him with another error . . . since there is 

 no such sheer height available on earth. 



It is true that in the above " Dialogue " 

 Galileo does not give the place of experi- 

 mentation and does not mention the leaning 

 tower. But what other locality in Pisa 

 would have been as favorable? Prom the 

 above data it follows that Galileo dropped 

 different weights of a variety of materials 

 and noticed which of them fell faster. 



1 Translation by H. Crew and A. De Salvio, New 

 York, 1914, pp. 62, 65, "First Day." 



That Viviani was in a position to speak 

 with authority follows from the fact that 

 soon after Galileo had published his "Dia- 

 logue concerning two New Sciences," 1638, 

 Viviani became his pupil and was in close 

 contact with him for three years, receiving 

 instruction which began with the theory of 

 moving bodies. Favaro- advances evidence 

 which shows that Galileo and Viviani became 

 quite intimate, Viviani admiring the old sage 

 and Galileo treating- the young man as if a 

 son. 



Florun Ca.jori 



University op California 



jonathan edwards on multidimensional 

 space and the mechanistic con- 

 ception of life 



If the Einstein conception of space is multi- 

 dimensional and inclusive of the essential con- 

 ceptions of time and place, then Jonathan Ed- 

 wards, whom John Fiske characterized as the 

 greatest mind of the Western World, may 

 prove to be the spiritual father of this geom- 

 etry. Thus wrote Jonathan Edwards:^ 



Supposing that there are two Particles or Atoms 

 of Matter perfectly equal and alike, which God 

 has placed in different Parts of the Creation. . . . 

 If they are perfectly equal and alike in themselves, 

 then they can be distinguished or be distinct only 

 in those Things which are called Circumstances ; as 

 Place, Time, Eest, Motion, or some other present 

 or past Circumstances or Relations. ... If God 

 makes two bodies in themselves every Way equal 

 and alike, and agreeing perfectly in all other Cir- 

 cumstances and Eelations but only their Flace. 

 then in this only is there any Distinction and Du- 

 plicity. The Figure is the same, the Measure is 

 the same, the Solidity and Eesistance are the same, 

 and every Thing the same, but only the Place. . . . 

 The Difference of Place, in this (the former) Case, 



2 Antonio Favaro, "Amici e Corrispondenti di 

 Galileo Galilei. XXIX. Vincenzio Viviani." Vene- 

 zia, pp. 8-19. 



1 " A Careful and Strict Enquiry into the 

 modern prevailing Notions of that Freedom of the 

 Will which is supposed to be essential to Moral 

 Agency, Vertue and Vice, Eeward and Punish- 

 ment, Praise and Blame," 1754, p. 243; "Of 

 God's Placing differently Similar Particles." 



