SURFACE-TENSION OF WATER BY THE METHOD OF JET VIBRATION. 311 



formation of the jet and which are rapidly extinguished. We see, however, that the 

 influence of these irregularities on the wave-length is not insignificant, even at a 

 considerable distance from the orifice. Thus, in the experiments mentioned, the 

 wave-lengths are at a distance of 10 cm. from the orifice in the mean 2 per cent., and 



at a distance of 20 cm., 0"3 per cent., smaller than is the wave-length at a distance of 

 30 cm. from the orifice ; if, therefore, the wave-length at 10 cm. or at 20 cm. distance 

 from the orifice had been used for the calculation of the surface-tension, a value 

 respectively 4 per cent, and O'G per cent, too great would have been obtained. 



The four experiments mentioned furthermore illustrate the influence of the viscosity 

 on the phenomenon, the magnitude of the wave-amplitudes at two places of the jet 

 with considerable mutual distance being measured (see the table on p. 310). 



Putting - = A.e ", we get for the four jets respectively 



(Jb 



e = 0-0271, e= 0-0212, 



In the above we have found (p. 289 (40)) 



e = 0-0213, 



e = 0-0187. 



p ca" \ rz, /L ( 2\pcd 2 k/ 

 From this formula we get the following results for /*, 



in = 0-0131, p. = 0-0129, p. = 0-0130, ^ = 0-0129. 



We see that these values do not differ much from the most generally adopted value 

 for p., namely, /x = 0-0125 (temperature, ITS C.). That they, however, are all greater 

 suggests, perhaps, a very small superficial viscosity. 



The correction of the formula to calculate the surface-tension, due to the effect of 

 the viscosity on the wave-length, is, according to the equation (41), on p. 289, deter- 

 mined by the coefficient 



\pca" 



