28o PROCEEDINGS OF THE COTTESWOLD CLUB 



at the top. Thus the pressure is reheved, large bubbles 

 of steam are formed throughout the water in the reservoir, 

 and nearly the whole of the contents is thrown up in huge 

 masses, hke projectiles from a gun, through the outlet-tube 

 and high into the air. 



The formation of the steam, and the mechanical work 

 done in lifting the mass of water, absorb so much energy 

 in the form of heat that the water remaining in the 

 reservoir sinks to the ordinary boiling point and below it 

 (as has been proved by actual thermometric observations), 

 and the action of the geysir subsides. But in the course 

 of more or less time new supplies of water percolating 

 through the rocks again fill the reservoir and the vertical 

 pipe, and new supplies of heat raise this water in tempera- 

 ture, until an explosion again occurs in the same way as 

 before. 



We have here, I think, a simple and adequate explana- 

 tion of all the phenomena characteristic of geysir-action ; 

 and it is easy to show on a small scale that, given such 

 conditions as those described above, results in every way 

 similar to those observed in the immense laboratorv of 

 Nature must and will occur. 



