

APPLICATIONS OF MARIOTTE'S LAW. 



263 



straight tube, hence 

 through this tube 

 water will flow out- 

 wards. 



If the water is to rise in 

 i strong jet, the bore of the 

 straight tube should be- 

 amch. wider than the aper- 

 ture at the pointed end of 

 ^he bent tube ; for in thafr 

 base the pressure of the 

 enclosed air approaches 

 more nearly to that at the 

 npper end of the straight 

 tube than to that at the 

 pointed end, that is, it is 

 Considerably less than that 

 it the smaller orifice, and 

 hence the water is thrown 

 upwards with considerable 

 force. It may happen 

 chat too much air has been 

 sucked out of the bottle, 

 ind in that case the water 

 which issues from the 

 jointed end will not pass 

 put through the straight 

 ube but will be driven 

 )ack by the external pres- 

 nio of the air. This may 

 be avoided by closing the 

 <>wer end of the straight 

 lube with the finger before 

 t is taken from the mouth ; 

 vhen the jet ceases, the 

 linger is withdrawn and 

 he water issues again, the 

 J3t being now higher than 

 efore. From time to time 

 ater should be added in 

 'lie open vessel in order to 

 laintaiii it at a pretty 

 niform height. 



