from The Century Dictionary and Cyclopedia
- n. Harbor dues.
Sorry, no etymologies found.
A highway, a bridge, a navigable canal, for example, may in most cases be both made and maintained by a small toll upon the carriages which make use of them: a harbour, by a moderate port-duty upon the tunnage of the shipping which load or unload in it.
To close with the American distinction, this revenue was _external_ or port-duty; but again, to soften it to the other party, it was a duty of _supply_.