CENTUUY II. fU 



give a diverse tone, as well as a diverse loud ness : 

 but they do not so ; for though the sound of the one 

 be louder, and of the other softer, yet the tone is the 

 same. Besides, in echoes, whereof some are as loud 

 as the original voice, there is no new elision, but a 

 repercussion only. But that which convinceth it 

 most of all is, that sounds are generated where there 

 is no air at all. But these and the like conceits, 

 when men have cleared their understanding by the 

 light of experience, will scatter and break up like a 

 mist. 



125. It is certain, that sound is not produced at 

 the first, but with some local motion of the air, or 

 flame, or some other medium ; nor yet without some 

 resistance, either in the air or the body percussed; 

 For if there be a mere yielding or cession, it pro- 

 duceth no sound ; as hath been said. And therein 

 sounds differ from light and colours, which pass 

 through the air, or other bodies, without any local 

 motion of the air ; either at the first, or after. But 

 you must attentively distinguish between the local 

 motion of the air, which is but &quot; vehiculum causae,&quot; 

 a carrier of the sounds, and the sounds themselves, 

 conveyed in the air. For as to the former, we see 

 manifestly, that no sound is produced, no not by air 

 itself against other air, as in organs, &c. but with a 

 perceptible blast of the air ; and with some resist 

 ance of the air strucken. For even all speech, which 

 is one of the gentlest motions of air, is with expulsion 

 of a little breath. And all pipes have a blast, as well 

 as a sound. We see also manifestly, that sounds are 



VOL. IV. G 



