WAVES. 439 



perceptible to our eyes, a phenomenon analogous 

 in its character, though developed by a precisely 

 opposite state of temperature, to the first move- 

 ment of air on land. By placing several lumps 

 of ice in a tumbler partly filled with water, these 

 movements can be very distinctly perceived ; 

 the cold particles in descending becoming partly 

 visible, in consequence of the effect of their 

 greater density upon the refraction of light; 

 but, in consequence of a peculiar law in the 

 constitution of water before noticed, at the 40th 

 degree on Fahrenheit's thermometer, further 

 movement of its particles from above downwards 

 is arrested. The attention of this singular and 

 beautiful provision has been previously consi- 

 dered. On the whole, however, the actual ex- 

 tent and amount of movement arising from this 

 cause must be slight, although it is doubtless 

 important as a means of preserving uniformity 

 of composition, with regard to the saline con- 

 tents and the solutions of the gases throughout 

 the whole mass of water. 



The movements with which we have thus 

 been occupying ourselves are removed from 

 ocular observation ; those which are next to 

 come under our notice, and which are among 

 the most sublime phenomena of the ocean, 

 appeal both to the ear and to the eye, as we 

 behold them agitating mass after mass of water, 



