<5o 



SCIENTIFIC RECREATIONS. 



corresponding with the elevation of the parent spring whence it issues. The 

 waterworks companies first pump the water to a high reservoir, and then it 

 rises equally high in our high-level cisterns. 



As an example of the force of water, a pretty little experiment may be 

 easily tried, and, as many of our readers have seen in a shop in the Strand 

 in London, it always is attractive. A good -sized glass shade should be 

 procured and placed over a water tap and basin, as per the illustration here- 

 with. Within the glass put a number of balls of cork or other light material. 

 Let a stop-cock, with a small aperture, be fixed upon the tube leading into 

 the glass. Another tube to carry away the water should, of course, be 



57. Water jet and balls. 



provided, but it may be used over again. When the tap is properly fixed, if 

 the pressure of the water be sufficient, it will rush out with some force, and 

 catching the balls as they fall to the bottom of the glass shade bear them up 

 as a juggler would throw oranges from hand to hand. If coloured balls be 

 used the effect may be enhanced, and much variety imparted to the experi- 

 ment, which is very easy to make. 



Water exercises an enormous pressure, but the pressure does not depend 

 upon the amount of water in the vessel. It depends upon the vessel's height, 

 and the dimensions of the base. This has been proved by filling vessels 

 whose bases and heights are equal, but whose shapes are different, each 

 holding a different quantity of water. The pressure at the bottom of each 



