HERO'S FOUNTAIN. 249 



the lower end of/, the jet ceases, and only a little air 

 is then ejected through the spout. At last, the water 

 from a having passed into th<e dish, and thence into &, 

 the vessel b is nearly filled. The apparatus may then be 

 inverted and the water allowed to flow back again into a, 

 or, as is the case in the fixed fountains, b may be 

 emptied by a stop-cock at the side, and a filled again by 

 removing f. 



Fig. 1 70 B represents a fountain made entirely of glass ; a, ft, c, d, 

 and / correspond to those parts in^L which are lettered similarly, and 

 the funnel e replaces the flat dish e e in fig A. The funnel should be 

 at least as capacious as a or &, because in this form of the apparatus 

 the jet does not fall back into it. The vessel b as filled through the 

 funnel e, the whole is inverted, the water thus fills ., and water is 

 then poured into e. 



Fig. 170 C shows a Hero's fountain, which may be easily con- 

 structed by means of glass bottles, tubing and corks. The several 

 parts have again -the same letters ; the bottle e serves in place of the 

 funnel in B, and the parts a, 5, c, d, and /, correspond to the parts 

 marked by the same letters in A and B. The bottle >e is tightly 

 closed by a cork through which passes the short tube g : and the long 

 tube c, which is continued downwards ; by blowing through the 

 short tube, the water is made to flow from e through c into the 

 bottle &, and the flow continues even when no more air is blown 

 in; the tube c acts now like a siphon, the action of which will 

 be explained immediately. The apparatus cannot be carried about 

 as a whole, nor set up without a proper support ; the bottles -a and e 

 should be placed near the edge of the table, and b upon a support of 

 jthe right height, or otherwise the putting together and the taking to 

 pieces of the apparatus is very difficult. First fill a and -e, close 

 them with their corks, and place both so that the tubes c a-nd d are 

 very near to one another ; next push the cork for b over the tube c 

 until it is opposite to d, seize both tubes with the left hand just 

 above the cork, and push the latter with the right hand over the end 

 of 1 1 ; now press the cork into the mouth of &, and place the latter 

 upon the supports which have been kept in readiness. The appa- 

 tratus is, of course, taken to pieces in inverted order. 



The explanation of the phenomena which take place 

 when liquid and gaseous bodies act mechanically 





