71 



city of his observations. "Why/ 1 says Aris- 

 totle in his curious book of Problems, " why is 

 sound better heard during* the night ? Because 

 there is more calmness on account of the ab- 

 sence of caloric (of the hottest)*. This absence 



* I have placed in a parenthesis, a literal version of the 

 term employed by Aristotle, to express in reality what we 

 now term the matter of heat. Theodore de Gaza, in his Latin 

 translation, expresses in the shape of a doubt what Aristotle 

 positively asserts. I shall remark on this occasion, that, 

 notwithstanding the imperfect state of science among the 

 ancients, the works of the Stagirite contain more ingenious 

 observations than those of other philosophers. It is in vain 

 we look in Aristoxenes (Lib. de Musica), in Theophilactus Si- 

 mocatta (de Qucestionibusphysicis), or in the 5th Book of the 

 Qu&st. nat. of Seneca, for an explanation of the nocturnal 

 augmentation of sound. A person deeply versed in the 

 knowledge of the ancients, Mr, Laurencit, has communicated 

 to me a passage of Plutarch (ed. Par., 1624, vol. ii, p. 721, 

 D), which confirms that of Aristotle, and which I shall cite, 

 from the simple version of Amyot. " Boethus le premier 

 interlocuteur, pretend que la froidure de la nuit fige et con- 

 dense Tair, et que Ton entend mal le son pendant le jour, 

 parce qu'il y a moins de vides. Ammonius, le second inter- 

 locuteur, rejette les vides de Boethus, et admet. avec Anax- 

 agore, que, de jour, le soleil remue Fair d'un mouvement 

 tremblant et plein de battement : que Ton entend mal le jour 

 a cause de la poussiere qui volette dans l'air, qui siffie et qui 

 murmure, mais que, la nuit, le branlement cesse. et par con- 

 sequent le sifilement de la poussiere. Boethus se justifie de 

 vouloir corriger Anaxagore ; mais il pense qu'il faut renoncer 

 aux sons des petits corps, et qu'il suffit d'admettre te branle- 

 ment et le mouvement d'iceux. L'air etant la substance 

 propre a. la voix, s'il est rassis, donne voie toute droite, unie 



