453 
the velocity of sound, made in Holland. 
sound along the basis 52", 37. Thus the mean velocity in 1' 
was 337 m ,39 = 1107,268 feet. 
The mean temperature at the time of these experiments 
at Zevenboompjes 7 0 , 41 
Kooltjesberg 8 , 54 ( centigrade 
Mean temperature of the air, 7 ,97 5 = t J 
Mean height of the barometer corrected for capillarity, and 
at o° cent , 
at Zevenboompjes o m ,7522 
Kooltjesberg o ,7 538 
Mean barometer - - - o ,7530 ~p 
Mean tension of aqueous vapour in the air, 
at Zevenboompjes o,oo737444 
at Kooltjesberg - 0,00706966. 
Mean tension - - 0,00722205 = F, 
which quantities substituted in the formula, we have for tem- 
perature o° cent, and in perfectly dry air the velocity of sound 
U'=s 331,85 metres = 1089,087 feet. 
