'produced by a Fluid in MotioJi. 



107 



millims. of mercury*. A glass tube, A, fig. 6, *3 metre long by 

 4 millims. internal diameter, was drawn out at one end to an 

 orifice 1*5 millim. in diameter, and was placed in the position 

 shown in the figure, the lower end dipping into a vessel of mer- 

 cury, B ; C represents the end of the stopcock. A scale was 

 attached to A to indicate the amount of diminution of pressure 

 (and consequent ascent of mercury in A) caused by the lateral 

 action of the jet of steam proceeding from C. The upper orifice 

 of A was placed exactly in the axis of the effluent jet. 



By looking through a jet of effluent steam of high pressure a 

 small inner cone (shown in the figure) is observed, to the apex 

 of which the greater number of particles of steam converge • 

 around and beyond thisc one there is steam of less density • and 

 it will be seen below that, beyond the apex of the cone, the 

 amount of lateral action diminishes considerably. 



The following results were obtained with a pressure of steam 

 equal to 1216 millims. of mercury t: — 



Distance of the orifice of A from the 

 orifice of C in millimetres. 



Height to which 

 the mercury as- 

 cended in A. 



Atmospheric pres- 

 sure (barometer 

 = 760 millims.) 

 reduced to 





millims. 

 196 

 228 

 180 

 126 



38 



27 



15 



millims. 

 564 

 532 

 580 

 634 

 722 

 733 

 745 





12 ,, (at the apex of the cone) ... 

 15 „ (beyond the cone"* 





75 



100 „ „ „ 





When the orifice of A was 1 millim. distant from the orifice 

 of C (a plane parallel to the one being at right angles to a plane 

 parallel to the other), and the centre of the orifice of A coinci- 

 dent with the centre of a cross section of the effluent jet, as in a, 

 fig. 6, the mercury, as stated above, rose in A to a height of 196 

 millims. When the centre of the orifice of A was placed in a 

 position midway between the centre and circumference of a cross 

 section of the effluent jet, as in (3, the mercury ascended to a 

 height of 105 millims. Finally, when the centre of the orifice 

 of A was placed very near the circumference of a cross section of 

 the effluent jet, as in 7, the mercury ascended only to a height 



* That is to say, from I "4062 to 2*1094 kilogrammes on a square centi- 

 metre, or from 20 to 30 lb. on a square inch. 



t Equal to 16874 kilogramme on a square centimetre, or to 24 lb. on 

 a square inch. 



