These are the measures which are now in use, and above the rest those of seven, eight, and ten syllables.  Our ancient poets wrote verses sometimes of twelve syllables, as Drayton’s Polyolbion.

  Of all the Cambrian shires their heads that bear so high,
  And farth’st survey their soils with an ambitious eye,
  Mervinia for her hills, as for their matchless crouds,
  The nearest that are said to kiss the wand’ring clouds,
  Especial audience craves, offended with the throng,
  That she of all the rest neglected was so long;
  Alledging for herself, when, through the Saxons’ pride,
  The godlike race of Brute to Severn’s setting side
  Were cruelly inforc’d, her mountains did relieve
  Those whom devouring war else every where did grieve. 
  And when all Wales beside (by fortune or by might)
  Unto her ancient foe resign’d her ancient right,
  A constant maiden still she only did remain,
  The last her genuine laws which stoutly did retain. 
  And as each one is prais’d for her peculiar things;
  So only she is rich, in mountains, meres and springs,
  And holds herself as great in her superfluous waste,
  As others by their towns, and fruitful tillage grac’d.

And of fourteen, as Chapman’s Homer.

  And as the mind of such a man, that hath a long way gone,
  And either knoweth not his way, or else would let alone,
  His purpos’d journey, is distract.

The measures of twelve and fourteen syllables were often mingled by our old poets, sometimes in alternate lines, and sometimes in alternate couplets.

The verse of twelve syllables, called an Alexandrine, is now only used to diversify heroick lines.

  Waller was smooth, but Dryden taught to join
  The varying verse, the full resounding line,
  The long majestick march, and energy divine.  Pope.

The pause in the Alexandrine must be at the sixth syllable.

The verse of fourteen syllables is now broken into a soft lyrick measure of verses, consisting alternately of eight syllables and six.

  She to receive thy radiant name,
    Selects a whiter space.  Fenton.

  When all shall praise, and ev’ry lay
    Devote a wreath to thee,
  That day, for come it will, that day
    Shall I lament to see.  Lewis to Pope.

  Beneath this tomb an infant lies
    To earth whose body lent,
  Hereafter shall more glorious rise,
    But not more innocent. 
  When the Archangel’s trump shall blow,
    And souls to bodies join,
  What crowds shall wish their lives below
    Had been as short as thine!  Wesley.

We have another measure very quick and lively, and therefore much used in songs, which may be called the anapestick, in which the accent rests upon every third syllable.

  May I govern my passions with absolute sway,
  And grow wiser and better as life wears away.  Dr. Pope.