6 HALF AN HOUR WITH THE WAVES. 



as that of the tides. How strange it seems that 

 our satellite, the nioon, although placed nearly a 

 quarter of a million of miles away from the earth, 

 should nevertheless be able to exert an unseen in- 

 fluence upon the oceans and seas of the globe. The law 

 of attraction silently exerts its force across that wide 

 gulf, and thus the moon pulls or draws each part 

 of the earth that happens to be turned immediately 

 under her towards herself. The solid part of the 

 globe she cannot affect the component parts are 

 already operated upon by forces too strong to admit 

 of it. But wherever there is matter whose ultimate 

 particles are so freely and loosely bound together 

 as in water, there will the lunar influence be felt. 

 Thus the moon's pull will result, out in the open 

 sea, in one huge wave being drawn upwards, and 

 this wave we call tidal. It travels onwards as the 

 earth revolves on her axis, and, when it reaches 

 continents or large islands, straits, channels, &c., 

 it rushes up the narrow areas and often rises in 

 height on account of being dammed up. Winds 

 long prevailing may retard its progress, and thus 

 produce a lower tide than usual ; or they may 

 assist the lunar influence, and thus effect a higher 

 one. Currents may be and often are produced by 

 tides meeting, after circling or skirting islands or 

 mainlands, and " rough seas" be the consequence. 

 These daily " tides " would occur exactly every 

 twelve hours if the moon were absolutely stationary. 

 But, seeing that she herself has a revolution to 



