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MR. P. O. PEDEKSEN ON THE SURFACE-TENSION OF LIQUIDS 



The first method is illustrated by fig. 12. Here abba represents one of the 

 profile lines of the jet (seen from above). L is a Nernst-lamp (1 amp. 220 volts), 

 the linear filament being vertical. The rays coming from L are reflected by the 



Fig. 12. 



mirror S and unite after reflection from the surface of the jet in the image L t . 

 When the profile line is a sinusoid the distance between the images L' and L! will be 

 equal to the wave-length. This distance can be determined with great accuracy, and 



ai 



Fig. 13. 



if the jet were perfectly free from alien vibrations this method would be able to give 

 very exact results. Unfortunately it has not been possible for me to produce a jet 

 so regular that I could make use of this method with real advantage. Even very 

 small deviations from the desired jet-form change the position of the images very 



