( ? ) 
cciver. In this manner, the Air contain’d between 
the outward and inward Receivers was exhaufted. 
Now here I was (ure, when the Clapptrr ftiould be 
made to ftrike the Bell, there would be adual Sound 
produc’d in the inward Receiver, the Air in which 
-was of the fame denfity with common Air^ and 
could fuffer no Alteration by the Vacuum on its out- 
fide, fo ftrongly was it fecur'd on all (ides. And as 
I faid before, that if the Sonorous Body fhould fuffer 
in any meafure, by being in a very rare Medium^. 
fo .as to contribute to the lofs of its Sound, that 
this Method ‘feem’d probable to difeover it. 
Thus all being ready for Trial, the Clapper was 
made to ftrike the Bel4 hut I found that there was 
no tranfmiffion of it thro* the Vacuum, tho’ I was 
fure there was adual Sound produc’d in the Recei* 
ver. 
This plainly (hews, and feems pofitively to confirm. 
That Air is the only Medium for the Propagation 
of Soundo 
