136 ANNUAL OF SCIENTIFIC DISCOVEEY. 



west end. On the south side there are two doors and one window, a 

 small orchestra ten feet high, and two Doric columns on each side of 

 the orchestra. 



POWER OF WAVES. 



In a paper on this subject before the British Association, 1862, 

 Prof. Rankine stated that the mechanical energy of a wave is half 

 actual and half potential (half being due to motion and half to ele- 

 vation), and the destructive power of a wave is double of that due 

 to the motion of its particles alone. The hydrostatic pressure of each 

 individual particle during the wave-motion is the same as if the liquid 

 were still. 



FOEMS AND ACTION OF WATEE. 



At the meeting of the British Association, 1862, one of the even- 

 ing meetings was devoted to a lecture from the well-known physicist, 

 Prof. Tyndall, on the " Forms and Action of Water." 



The Professor dwelt at the outset on the energy of molecular 

 forces. In the combination of oxygen and hydrogen to form a gallon 

 of water, weighing ten pounds, an energy was expended the atoms 

 clashed together with a force equal to that of a ton weight let fall 

 from a height of 23,757 feet. In falling from the state of vapor to 

 that of water, an energy was exerted equal to that of a ton falling 

 from a height of 3,700 feet, or of one hundred weight from a height 

 of 74,000 feet. The moving force of the stone avalanches of the 

 Alps was but as that of snow-flakes compared with the energy in- 

 volved in the formation of a cloud. In passing finally from the 

 liquid to the solid state, the atoms of ten pounds of water exercised 

 an energy equal to that of a ton weight falling down a precipice five 

 hundred and fifty feet high. The lecturer then halted to consider 

 some of the phenomena connected with water in its vaporous state. 

 Its action upon radiant heat was extraordinary. Though forming 

 only about five-tenths per cent, of the entire atmosphere, for every 

 ray of terrestrial heat struck down by the air, fifty, sixty, or seventy 

 rays were destroyed by the aqueous vapor. The vapor of the lec- 

 ture-room was shown by condensing it on the surface of a vessel con- 

 taining a freezing mixture, on which it precipitated itself in such 

 quantity that, when scraped off, a snowball was formed of the con- 

 densed vapor. Aqueous vapor was the "barb" of our atmosphere; 

 it permitted the solar rays to reach the earth, but intercepted the 

 terrestrial rays in their escape towards space. The Desert of Sa- 

 hara showed us what would be the effect of its removal. There, 

 where the " soil is fire and the wind is flame " during the day, the 

 nights are intensely cold, - - ice, in fact, has been known to be formed. 

 Were the aqueous vapors removed from the air which covers Eng- 

 land, no doubt a single summer night would destroy all plants inca- 

 pable of bearing a freezing temperature. The Professor then dwelt 

 briefly on the liquid state of water, -and passed on to consider its solid 

 form. Ice was chosen, and shown to be eminently brittle. Pieces of 

 it, when placed together, froze together. This freezing was shown 

 to occur in hot water. The ice was scraped to fine powder, and the 





