INVESTIGATED I!Y TMK MKTHOD OF JET VIBRATION. 



375 



not to the jet itself. To get an idea of the size of the amplitude of the jet I have 

 taken photographs of different jets, and afterwards by help of an object-micrometer 

 measured the largest and smallest diameters at a distance of 3 to 4 cm. from the 

 apertures. The results of these determinations are given in Table IX. ; it appears 

 that the amplitude of the jet is somewhat greater than the amplitude of the orifice, 

 and that it increases with the pressure. 



Therefore the above conclusion respecting the permissible amplitude will not always 

 hold good. The pressure, about 70 cm., used by the measurements made here, lies, 

 however, within the limits investigated in Table VII. (alwut 42 up to 97 cm. 

 pressure). 



The nature of the liquid may also play a part ; but that has hardly any great 

 influence as far. as these investigations are concerned. 



In order to attain greater certainty on this point I have determined the surface- 

 tension of some other liquids by measurements with orifices III., V., and VII. ; the 

 results obtained are shown in Table X. This is calculated as follows : In the same 

 manner as in Table VII., T I8 is determined for each individual orifice, and for each of 

 these the mean value is taken. The mean value for all the measurements with 

 apertures VII. and V. is taken as the correct value of the surface-tension for the 

 liquid in question. Table X. contains the deviations from the mean value found in 

 this manner, with reference to the orifices in question, shown as a percentage of the 

 surface-tension. 



TABLE X. 



It appears that the results for orifice VII. are generally a little larger than for 

 orifice V. The difference lies, however, within the limit of error, as the deter- 

 mination for orifice V. is difficult. It proves, however, that under the present 

 conditions the amplitude for orifice VII. is sufficiently small. On the other hand, 

 however, it also appears that the values for orifice III. are, as a rule, a little too 

 small. It would therefore be natural to carry out the measurements with orifices 

 VII. and V. The determination is, however, in reality made with orifices VII. and 

 III., for the following reason: The amplitude for orifice V. is so small that the 

 determination of the wave-length is difficult and uncertain, especially for liquids with 

 small surface-tension, or, in other words, large wave-lengths. On the other hand, 



