Few poems illustrate meters perfectly; please see the explanation at the bottom of the main page in this unit.
Dactylic heptameter breaks down into tetrameters and trimeters--or so it seems so far.
In "Martin Relph," Robert Browning concocted an irregular heptameter that sometimes seems heavily-substituted iambics and sometimes anapestic. But some lines are also a rough dactylic heptameter:
/ *
* | / * | / *
* | / * | /
* * | / *
/
Gives by her fate fair warning to such acquaintance
as play the spy.
Henceforth who meddles with matters of state
above them perhaps will learn
That peasants should stick to their ploughtail,
leave to the King the King's concern.