176 



h- -4 



o 100,000 



Instantaneous Pro^Jlc& 



Figure 58. — Tides and currents of frietionless progressive wave. 



200,000 feet 



341. It readily may be shown that a progressive wave would be 

 propagated through an endless deep canal of uniform section, from any 

 fluctuation of the water surface at the entrace, whether harmonic or 

 otherwise, if the flow were frietionless. Such a wave would also be 

 propagated, under the same conditions, through a canal of finite 

 length, if the energy transmitted could be wholly absorbed at the far 

 end. As will be shown later, the tidal flow in an estuary of the usual 



