|  | The harbour has been scoured out by the fast flowing outward
    tides induced by the sea walls. It is fifty feet deep in the centre with sharp sloping
    banks. The piers are made of sand and glue. The two junks have thirty slaves, provisions
    and cargo aboard. They will leave the harbour on each day which is a multiple of three.
    There are three city guards on each junk. Piers are fifty feet long, fifteen feet wide and
    fifteen feet above high tide level. |  |