Alexander Adams (c. 1814)

Devenish is the name of a parish, as well as an island. Devenish island itself is tiny (no-one lives there today at all) and didn?t have an active church on it in 1818. (If I recall correctly, the Church of Ireland parish church is at Trory, on the mainland). I?d say it?s more likely Sarah was baptised in the parish, than on the island itself.

You don?t say what denomination Sarah was but I?d hazard a guess it was Church of Ireland. Tradition was to marry in the bride?s church, so assuming her family didn?t move, I?d expect Sarah?s marriage to be in the same parish as her baptism. I don?t think the Devenish COI parish records are on-line anywhere. There is however a copy in PRONI, Belfast as follows:

C.I. Devenish (Clogher diocese)?Baptisms, 1706, 1798, 1800-23 and 1828-73; marriages, 1800-24 and 1829-61; burials, 1801-22 and 1828-1939; vestry minutes, 1739-1829.

Sarah?s likely to have married around 1838 ? 1840. Those records are not on-line and a personal visit to PRONI is required to access them. Alternatively you can write to the Rector of the Church but be aware that the Church of Ireland charges for searches (usually ?19 an hour if conducted by the Rector/Vicar).