40 



On some Effects produced by a Fluid in Motion. 



ished; the discs were of nearly equal size (C, fig. 3) ; and when 

 the flow was very much diminished (that is to say during the 

 production of the most base notes), cylinders of air alternated 

 with discs of water (D, fig. 3). 



The air was collected in a half-litre flask, inverted over the 

 lower orifice of A, fig. 2, the exact time necessary to fill it being 

 noted, and the amount of air passing through the tube in a 

 second calculated therefrom. 



When the flow of water was so small that impulses not fol- 

 lowing each other with sufficient rapidity to produce a musical 

 note were heard, the eye could follow the air-cylinders in their 

 passage down the tube, and by attaching a small divided scale to 

 the side of the tube A, fig. 2, and simultaneously checking the 

 flow and closing the orifices, the number of air-discs in an inch 

 could be counted ; and thus, the amount of air and of water 

 passing through the tube per second, the capacity of the tube, 

 and the number of air-discs in it at one time being known, the 

 number of impulses produced per second could be roughly 

 calculated. 



When the flow had attained a certain degree of quickness, the 

 air-discs coalesced into larger ones so rapidly that the number 

 in an inch could not be counted. 



All the notes were base; and the only variation capable of being 

 produced was from a base note to distinct impulses incompetent 

 from their slowness to produce a note. 



The following Tables may serve as examples of some of the 

 results obtained : it is obvious that the number of impulses per 

 second could not be determined with any great accuracy : — 



I. An 18-inch vertical tube, A, fig. 2. Caoutchouc with four 

 orifices, B, fig. 2. 



Water 



passing through the tube 

 per second. 



Air passing 



through the tube 



per second. 



Number of impulses 

 per second. 



cub. centims. 



cub. centims. 





25 





Air did not enter. ! 



v Could not be de- 



21-739 





•333 



termined, on 



17-241 





2-403 



account of the 



15151 





2-994 



too rapid coal- 



11-111 





4-761 



escence of the 



10-638 





5-263 



J air discs. 



5-263 



Highest note produced. 



4-761 



676 



3-906 



Lower note than preceding. 



4-346 



60-3 



3-571 



>» »t » 



4-166 



566 



2-941 



H t> »> 



3-787 



49-2 



1-872 



Most base note. 



3-787 



38-2 



1-766 



Distinct impulses. 



3-703 



30-8 



•636 



»» >» 



2-564 



i 



14-5 



