Curiosities of Science. 183 



peculiar colour to a solution of carburetted hydrogen, to the 

 luxuriance of the tropical vegetation, and to the quantity of 

 plants and herbs on the ground over which they flow. Hurn- 

 ooldt's Aspects of Nature, vol. i. 



GKEAT CATARACT IN INDIA. 



Where the river Shirhawti, between Bombay and Cape Co- 

 morin, falls into the Gulf of Arabia, it is about one-fourth of a 

 mile in width, and in the rainy season some thirty feet in depth. 

 This immense body of water rushes down a rocky slope 300 feet, 

 at an angle of 45, at the bottom of which it makes a perpen- 

 dicular plunge of 850 feet into a black and dismal abyss, with 

 a noise like the loudest thunder. The whole descent is there- 

 fore 1150 feet, or several times that of Niagara; but the volume 

 of water in the latter is somewhat larger than in the former. 



CAUSE OF WAVES. 



The friction of the wind combines with the tide in agitating 

 the surface of the ocean, and, according to the theory of undu- 

 lations, each produces its effect independently of the other. 

 Wind, however, not only raises waves, but causes a transfer of 

 superficial water also. Attraction between the particles of air 

 and water, as well as the pressure of the atmosphere, brings its 

 lower stratum into adhesive contact with the surface of the sea. 

 If the motion of the wind be parallel to the surface, there will 

 still be friction, but the water will be smooth as a mirror ; but 

 if it be inclined, in however small a degree, a ripple will appear. 

 The friction raises a minute wave, whose elevation protects the 

 water beyond it from the wind, which consequently impinges 

 on the surface at a small angle : thus each impulse, combining 

 with the other, produces an undulation which continually ad- 

 vances. Mrs. Somerville's Physical Geography. 



HATE AT WHICH WAVES TRAVEL. 



Professor Bache states, as one of the effects of an earthquake 

 at Simoda, on the island of Niphon, in Japan, that the harbour 

 was first emptied of water, and then came in an enormous wave, 

 which again receded and left the harbour dry. This occurred 

 several times. The United-States self-acting tide-gauge at San 

 Francisco, which records the rise of the tide upon cylinders 

 turned by clocks, showed that at San Francisco, 4800 miles from 

 the scene of the earthquake, the first wave arrived twelve hours 

 and sixteen minutes after it had receded from the harbour of 

 Simoda. It had travelled across the broad bosom of the Pacific 

 Ocean at the rate of six miles and a half a minute, and arrived 

 on the shores of California : the first wave being seven-tenths of 



