38 



Mr. G. F. Rodwell on some Effects 



occurred at 8 inches from the orifice of the delivery-tube, and 

 half a litre of air was carried down in 1 minute 7 seconds. 



Half a litre of air was 

 carried down in 

 Collision 5 inches from orifice of delivery-tube 2 min. 10 sec. 



33 " 33 33 33 }> " >f *" f , 



V. The delivery-tube used in Experiment III., the stream 

 flowing at the rate of half a litre in 68 seconds, was substituted 

 for the delivery-tube used in the last experiment. 



Before diminishing the efflux from the vertical tube, the col- 

 lision took place at 14 inches from the orifice of the delivery- 

 tube, and half a litre of air was carried down in 2 minutes 

 6 seconds. Half a litre of air was 



carried down in 

 Collision 7 inches from orifice of delivery-tube 2 min. 25 sec. 



a & a jf if 33 4 a ^O 33 



From the above experiments it is evident that the quantity of 

 air carried down by a stream of water is greatest when the colli- 

 sion of the stream with water takes place at the point where 

 the stream breaks up, and gradually diminishes as the distance 

 between the orifice from which the stream issues and the point 

 of collision decreases. 



The effect of allowing a stream of water to flow through a 

 vertical tube of the same diameter as the stream, and the upper 

 part of which freely communicates with the atmo- 

 sphere, was next tried. 



To the upper orifice of a tube 18 inches long 

 and ^ ths of an inch diameter (A, fig. 2), a piece 

 of caoutchouc tubing, B, having four small orifices 

 in its circumference, was adapted : the delivery- 

 tube C made use of in Experiment I. was con- 

 nected with the upper part of the caoutchouc, so 

 that the orifices in the caoutchouc were midway 

 between the orifices of C and A. The lower end 

 of A was curved, and dipped 3 J inches below the 

 surface of water. 



When C was caused to deliver its maximum 

 quantity of half a litre of water in 20 seconds, 

 the stream flowed down the tube into the vessel 

 below, exactly as it would have done if the upper 

 part of A had not communicated with the atmo- 

 sphere ; but when the flow was diminished, air 

 began to enter, and was carried down by the 

 stream ; on further diminishing the flow, the co- 

 lumn in the tube assumed a peculiar banded 

 appearance, and a base note was produced, which 



Fig. 2. 

 cf 



u 



