o.

      O.N. o remains o:  boldin, bolle, brod,
          costlyk, loft, rock, etc. 
      O.N. o + g > ow in low.

    u.

      O.N. u generally remains u:  bught, buller,
          clunk, cunnand, lucken, ugg, clubbit,
          drucken, skugg.  The sound of u in O.N.,
          however, was approximately that of oo in “foot.” 
      O.N. u > [-u] in drook.

    y.

      O.N. y always becomes i, written i, y:  big,
          birr, filly, flit, trig, wyndland,
          gylmyr.  The O.N. y had approximately the value
          of Germ. ue.

    ae.

      O.N. ae > e in ettle.

    oe

      O.N. oe > e in gleg, glegy, appears as u in
          slut. 
      O.N. oe, u-v-umlaut of a, becomes ae, written
          a:  daggit, ragweed, tangle. 
      O.N. oe, u-umlaut of a in originally open syllable,
          like open a, > [-e] in spale.

      Hence u-umlaut does not appear in loanwords.

    ja (ia).

      O.N. ja > a in assle-tooth, harn, starn.
        > e in sker and stern.

    joe (ioe).

      O.N. joe > a in tarn. 
      O.N. joe > i before r in firth, gyrth
          (gjoerth), gyrthin.

    LONG VOWELS.

    [-a].

      O.N. [-a] regularly > [-e], written a, ai, ay,
          ae, ei (?):  baith, blae, bray, braith,
          fra, frae, lait, craik, ra, saikless,
          spay, etc. 
      O.N. [-a] + g > aw, awch, aigh, aich,
          awsome, law, sb. law, adj. lawch, beside
          laigh and laich in N. Sco. 
      O.N. [-a] + l > ow in chowk (O.N. kjalki).

[-e].

O.N. [-e] remains in ser, seir.
[-e] > [-ae], written a, in fallow. 
O.N. [-e] before tt > i, written y, in tytt. 
Cp. titt in W.Norse dial.