Skip to main content

Full text of "Galileo's Experiments from the Tower of Pisa"

See other formats


Early Journal Content on JSTOR, Free to Anyone in the World 

This article is one of nearly 500,000 scholarly works digitized and made freely available to everyone in 
the world by JSTOR. 

Known as the Early Journal Content, this set of works include research articles, news, letters, and other 
writings published in more than 200 of the oldest leading academic journals. The works date from the 
mid-seventeenth to the early twentieth centuries. 

We encourage people to read and share the Early Journal Content openly and to tell others that this 
resource exists. People may post this content online or redistribute in any way for non-commercial 

Read more about Early Journal Content at 
journal-content . 

JSTOR is a digital library of academic journals, books, and primary source objects. JSTOR helps people 
discover, use, and build upon a wide range of content through a powerful research and teaching 
platform, and preserves this content for future generations. JSTOR is part of ITHAKA, a not-for-profit 
organization that also includes Ithaka S+R and Portico. For more information about JSTOR, please 

Octobeb 29, 1920] 




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," 1 Galileo lets Sagredo say: 

But I, Simplicio, who have made the test can as- 
sure you that a camion 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 only 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 Simplicio 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. 

i 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 2 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 

Florian Oajori 

University of California 


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: 1 

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, Best, Motion, or some other present 
or past Circumstances or Belations. ... If God 
makes two bodies m themselves every Way equal 
and alike, and agreeing perfectly in all other Cir- 
cumstances and Belations but only their Place. 
then in this only is there any Distinction and Du- 
plicity. The Figure is the same, the Measure is 
the same, the Solidity and Besistance are the same, 
and every Thing the same, but only the Place. . . . 
The Difference of Place, in this (the former) Case, 

2 Antonio Favaro, "Amiei e Corrispondenti di 
Galileo Galilei. XXIX. Vincenzio Viviani." Vene- 
zia, pp. 8-19. 

i " 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, Beward and Punish- 
ment, Praise and Blame," 1754, p. 243; "Of 
God's Placing differently Similar Particles."