It could be the result of chronologically and essentially different changes.
1) The rejection (loss) of nasals before fricativesf, θ, s, h.
a > ō OHG gans > OE gōs
i > ī Goth. sinÞs > OE sīÞ (trip)
u > ū OHG uns > OE ūs (us)
2) The loss of [h] before d.
OE mæ™den (maiden) – mæden
OE sæ™de – sæde (said)
3) As a result of contraction(стягування) of two neighbouring vowels always tended to contract forming a long vowel.
slahan > sleahan > sleaan > sleān
sehan > seohan > seoan > sēon (see)
Note: if i is contracted it causes umlaut of the preceding vowel.
*saiw > s æ (море)
O.Irish drui – OE dry (жрець)
(друїди – ірландські священники)
In the 18-19-th centuries another change occurred – lengthening of vowelsbefore ld, nd, mb.
climban – clīmban
The lengthening did not occur if the combination was followed by a third consonant.
cild > cīld, but the pluralcildru remained unchanged. Hence the differnce in root vowels of Mod.E : child and children.
