Plate ix. top. Dike under construction on a salt marsh. A tide gate will be 

 built across stream in foreground, bottom. A large tide gate controlling 

 drainage from a 1,200-acre salt marsh. Each tide gate opening measures 

 three and one-half by six feet. Supporting piles, in this case forty feet long, 

 are driven to solid substrata. The tide gate is here shown at low tide; the 

 arrow indicates normal high tide level. 



