Cambridge Philosophical Society. 469 
Mean amount of ozone with the box suspended at the height of 
25 feet. 
1859. December 24 hours’ exposure =3°0 48 hours’ exposure =5:0 
1860. January... 24 hours’ exposure =3°9 48 hours’ exposure =4'5 
February 24 hours’ exposure =3°7 48 hours’ exposure =5°4 
? b] 
March ... 24 hours’ exposure =5°9 48 hours’ exposure =6°4 
Mean amount of ozone with the box suspended at the height of 
40 feet, March 1860, with twenty-four hours’ exposure =7'l. 
CAMBRIDGE PHILOSOPHICAL SOCIETY. 
[ Continued from‘vel. xvii. p. 316.] 
October 31, 1859.—A communication was made by Mr. Hopkins 
«“‘On the construction of a new Calorimeter for determining the 
Radiating Power of the Surfaces of Heated Bodies.” 
November 14.—A communication was made by the Master of 
Trinity College ‘‘On the Mathematical part of Plato’s Meno.” 
November 28.—The Rev. Dr. Donaldson read a paper “On the 
Origin and proper value of the word ‘ Argument.’ ”’ 
The author first investigated the etymology and meaning of the 
Latin verb arguo, and its participle argutus. He showed that arguo 
was a corruption of argruo = ad gruo; that gruo (in argruo, ingruo, 
congruo) ought to be compared with xpotw, which means ‘to dash 
one thing against another,”’ especially for the purpose of making a 
shrill, ringing noise; that arguo means ‘‘ to knock something for the 
purpose of making it ring, or testing its soundness,” hence “to test, 
examine, and prove anything;”’ and that argutus signifies ‘“‘ made to 
ring,” hence ‘making a distinct, shrill noise,” or “tested and put 
to the proof.” Accordingly argumentum means id quod arguit, ‘ that 
which makes a substance ring, which sounds, examines, tests, and 
proves it.” 
It was then shown that these meanings were not only borne out 
by the classical usage of the word, but also by the technical appli- 
cation of ‘‘argument” as a logical term. For it is not equivalent 
to ‘argumentation,’ or the process of reasoning; it does not even 
denote a complete syllogism; though Dr. Whately and some other 
writers on logic have fallen into this vague use of the word, and 
though it was so understood in the disputations of ;the Cambridge 
schools. The proper use of the word ‘‘argument”’ in logic is to 
denote ‘‘ the middle term,” 7. e. ‘‘the term used for proof.” Ina 
sense similar to this the word is employed by mathematicians; and 
there can be no doubt that the oldest and best logicians confine the. 
word to this, which is still its most common signification. 
_ The author@entered at some length into the Aristotelian definition 
of the enthymeme, which may be rendered approximately by the word 
“argument.” He also explained how the words ‘topic’ and 
‘‘argument”’ came to denote the subject of a discourse or even of a 
