130 ANNUAL OF SCIENTIFIC DISCOVERY. 



to bo on an average of 22,000 feet, a result correspomlino; with 

 souniliniis niaile. 



The force of oeean waves has been ealcnlated. During a storm 

 on the western coast o( Scollaml. in March. 1845, tiie force of the 

 waves was estimated at 6,000 pounds per square foot. It wouhl 

 seem that the immense wave, which, like a wall oO feet hiirh, mov- 

 ing with resistless velccity, struck the ship-ot-war " ^Monongahcla" 

 broadside, in the harbor "of 8l. Thomas, and ilrovc her from her 

 moorings, forcing her over the tops of the warehouses, and leav- 

 ing her7 when the wave receded, high and dry on the coral reefs 

 of" the island, must have had a force even greater than 6,000 

 pounds to the square foot. 



FORCE OF WATER. 



According to the Abbe Moigno, — 



Per 



secoud. 

 M. 



RETARDED EBULLITION. 



Krebs has continued an investiafvition, begun some vears asfo 

 by Dufour, on some of the phenomena of retarded ebullition. 

 The experiments were made in a retort connected with an air- 

 pump, the water having previously been boiled several times to 

 get rid o( air in solution. After connection with the pump, the 

 water is again brought to the boiling-point, and then the heat is 

 withdrawn, and the pump set to work. When a vacuum of 11 

 inches was obtained, and the temperature of the water had fallen 

 to 107"'' F., it was found necessary to pump with caution, as at that 

 point the ebullition is likely to be violently reproduced. But that 

 stage being passed, it was found possible to get a perfect vacuum, 

 and allow the temperature of the water to sink to 86*^, or 104:° F. 

 without any ebullition. At this low temperature and pressure, 

 however, violent ebullition can be set up by several means. 

 Among these, he mentions two which he thinks may aft"ord expla- 

 nations of some boiler explosions. One is a sudden application 

 of heat ; the other is a shaking of the liquid. The latter seems 

 unlikely to be realized in a large bi>iler; but the former, we think, 

 may liappen when, for example, after a fire has been banked for 

 some time, and the temperature and pressure allowed to fall, a 



