﻿Instability of Gaseous Jets. 



371 



Table I. 

 Holes in thin plates. Thickness of plates 0*15 mm. 



Diam. of Orifice 

 in mm. 



Mean pressure in cm. of 

 water required for 



Mean 

 of fl 



length (cm.) 

 ame when 



Flaring. 



Maximum 



Sensitive- 

 ness. 



Minimum 

 Sensitive- 

 ness. 



Flaring. 



Max. 



Sens. 



Min. 

 Sens. 



0619 



313 



30-6 



160 



19-5 



21-0 



13-8 



0-643 



39-0 



36 



190 



20-5 



235 



17-5 



0-719 



365 



320 



18-0 



22-0 



25 



19-0 



0905 



36-0 



33-0 



17-5 



37-0 



41-0 



290 



1-107 



34-0 



33-0 



230 



38-0 



520 



42-0 



1-30 



12-6 



11-6 



60 



38-5 



540 



37-0 



2-0 



100 



9-0 



4-0 



350 



60-0 



450 



30 



50 



40 



2-7 



50-0 



65-0 



60-0 



Experiments were then made with jets from narrow glass 

 tubes ; a number of observations are given in the following 

 table. It will be seen that the range of pressure for sensi- 

 tiveness is extremely small, in some cases the numbers in 

 columns 4 and 6 being the same. A remarkable feature of 

 the jets from tubes is the extreme suddenness of the transi- 

 tion from a condition of stability to one of flaring ; in some 

 cases the slightest touch with the finger upon a large gas- 

 bag would be sufficient to bring the flame from the one 

 condition to the other. 



In place of short tubes, in which the irregularity of the 

 ends would probably have produced considerable effect, we 

 used thick-plate orifices, and it is interesting to observe, in 

 Table II. (p. 372), that as the diameter increases, that is as the 

 length becomes less important, the sensitiveness begins to show 

 itself. The flaring-pressure for a constant diameter decreases 

 with the length in the case of every tube in Table II., but it 

 increases with the thick-plate orifices. (Compare the follow- 

 ing, Table II. tube no. 3, thick- plate no. 2, Table 1. orifice 

 no. 5.) 



It thus appears that any tubularity of the orifice from 

 which the jet issues, in general lowers the flaring-pressure 

 and diminishes the sensitiveness for notes of high pitch ; 



2 C 5 2 



