146 PROCEEDINGS OF THE AMERICAN ACADEMY 



From Regnaidt's experiments on the velocity in pipes I find by 

 graphical means 331.4 m- in free air, which is very similar to the above. 



Calculation from Properties of Gases. 



K= speoific heat of gas at constant pressure. 



k = " " " " volume. 



p = pressure in absolute units of a unit of mass. 



v = volume " " " " 



fx = absolute temperature. 



J = Joule's equivalent in absolute measure. 



K_ 



k' 



7 = 



General formula for all bodies : — 



1 



7 = 



~JK 



; \dX \d fl ) p 

 -. J=-- t—\ (—) -2L 



& \dn/v \dp.)p 7-1" 



/— Y 



fdv\2 



Also, «/= — 



/do\ v* 



Application to gases ; Rankine's formula is, — 

 pv = R(n—m -\, 



&W (* + »-**). 



If a„ is tbe coefficient of expansion between 0° and 100°, then 



whence 



M = — (1 + -00635 m); 



Of 





