ON TIDES AND TIDAL ACTION IN HAKBORS. 



221 



depends upon the unchanged factors of area and form of basin, height 

 of tide, and character of the material forming the bar. 



EFFELCT OF SlNK.riC STONt-FLEET ON CH^RLFSTON BAf\ 



^ 



WW 





■m0 



An interesting instance of this manitenance of the depth of channels 

 from a determinate tidal basin is furnished by the effects, of the ob- 

 structions placed in the channel over Charleston Bar during the war of 

 the rebellion. On the accompanying diagram is seen the " stone fleet " 

 sunk in the main channel, which at that time had twelve feet of water 

 at low tide where the figure 7 indicates the present depth. There was, 

 moreover, another channel, making out more to the southward, with 



