522 Prof. R. Threlfall and Mr. J. F. Adair. On the 



which, is very much greater than the volume actually occupied by the 

 explosive, and that the pressure at a distant point is inversely propor- 

 tional to the distance from the centre of the sphere, the pressure at 

 20 yards distant would be approximately 64*4 atmospheres of 

 1,014,412 dynes per sq. cm. each. This value for an atmosphere has 

 been taken as representing Tait's value, which he defines by 152*3 

 atmospheres = 1 ton weight per square inch, at Edinburgh (?). 

 For pressures considerably below this, Tait's low pressure formula is 

 applicable. If the sphere supposed to be occupied by the explosive 

 is less than 1 foot in diameter, the pressure at a distant point would, 

 on the above suppositions, be proportionately diminished; and at 

 greater distance than 20 yards it would be further proportionately 

 diminished. Viscosity would aid in further diminishing the pressure, 

 so that on the whole, for the space between the gauges, it seemed 

 advisable to use the low pressure formula as given by Tait. 

 This formula is — 



Average compressibility of sea- water at low pressures is 



481 x 10-7-340 x 10" 9 t + 3 x 10~ 9 1 2 



per atmosphere increase of pressure at temperature t, 152*3 atmo- 

 spheres being = 1 ton weight per square inch. 



Taking such an atmosphere as 1,014,412 dynes par sq. cm., we thus 

 get— 



E = 1014412 



9 481 x 10-7 - 34U x 10-n + 3 x 10~ y t*' 



The following table gives the values of this for the temperatures of 

 the observations. 





Coefficient of 





Coefficient of 



Temperature. 



resilience, E#. 



Temperature. 



resilience, E#. 



13-0 



2-2957 xlO 10 



15-5 



2-3293 x 10 10 



133 



2-2998 



15-8 



2-3332 



134 



2-3011 



16-0 



2-3358 



13-5 



2-3025 



17-0 



2-3489 



14-1 



2-3106 



17-5 



2-3553 



14-3 



2-3133 



17-6 



2-3566 



14-5 



3-3160 



18-0 



2-3617 



15-2 



2-3253 



18-5 



2-3681 



15-3 



2-3266 



20-0 



2-3868 



General Formula for the Velocity of Sound. 

 The formula on p. 516 thus becomes — 



Velocity = *J "p-"ij^o J 

 E# Jcp 



