A third form of alliteration, though much less important and frequent than these two, occurs when the second accented syllable of the second hemistich shares in alliteration, in addition to the first accented syllable. There are then two different pairs of alliterative sounds distributed alternately between the two hemistichs. The commonest form of this double alliteration of the whole line is represented by the formula a b | a b, as
_hwæt! we =G=[=á]r=d=éna in =g=[=é]ar=d=águm._ Beow. 1.
_=Sc=ýldes =é=aferan =Sc=édelandum =í=n._ Beow. 19.
_=h=ílde=w=[=æ´]þnum ond =h=éaðo=w=[=æ´]dum._ Beow. 39;
_þ[=a] =w=[=æ´]ron =m=ónige þe his =m=[=æ´]g =w=ríðon._ Beow. 2982. _=h=w[=í]lum for =d=úguðe =d=óhtor =H=r[=ó]ðg[=à]res._ Beow. 2020;
verses corresponding to the formula a a | b b are not found in early poetry. No doubt certain instances of this double alliteration may be accidental, but others seem intentional.
The foregoing rules as to alliteration are strictly observed in the early and classic poetry, but in later times certain licences crept in. Three of these may be noticed. (i) The second accented syllable of the second hemistich is allowed to carry the alliteration instead of the first accented syllable,
_=l=[=á]stas =l=égde oðð[æ´]t h[=e] ge=l=[=æ´]dde._ Gen. 2536.
(ii) Both accented syllables of the second hemistich alliterate with one accented syllable of the first hemistich,[84]
_me =s=éndon t[=ó] þ[=e] =s=[=æ´]men =s=nélle._ Byrhtnoth 29.
(iii) The four accented syllables of the line all alliterate together,
_=G=ódwine ond =G=ódw[=i]g =g=[=ù]de ne =g=[=ý]mdon._ Byrhtn. 192.
In the majority of cases the same alliterative letter is not employed in two successive lines, but we find cases like
_þ[=a] t[=o]=b=r[=æ´]d Sámson =b=[=é]gen his éarmas þæt þ[=a] r[=á]pas to=b=úrston þe he mid ge=b=únden wæs._ Ælf. Judges 269;
and earlier in Andreas 70, 197, 372, 796, 815, 1087, &c., or in Beowulf 403, 489, 644, 799, 865, 898, &c.
_swýlce he [=a]=f=[=é]dde of =f=íxum tw[=á]m ond of =f=[=í]f hl[=á]fum =f=[=í]ra cýnnes =f=[=í]f þ[=ù]sendo; =f=[=é]ðan s[=æ´]ton._ An. 589 ff.
This usage, which in Middle English became very popular, is noticeably frequent in the poem of Judith, probably with a view to emphasis. Many examples of such pairs of verses are to be found collected by Dr. A. Brandeis from Ælfric.