try ulster architectural history society
some devitt marriages all too late but no births or burials from
https://www.ancestryireland.com/DEVITT JAMES 1850 father BERNARD Armagh
DEVITT JAMES 1851 Down
DEVITT JAMES 1851 Down
DEVITT JAMES 1851 father WILLIAM Antrim
DEVITT JAMES 1869 Down
no trace in Belfast street directories up to 1819
http://www.lennonwylie.co.uka will did exist for a James in Cullin. Cullin townlands existed in Cavan, Fermanagh, Meath. see
https://apps.proni.gov.uk/ProniNames_which suggests Co Fermanagh.
by ear rather than spelling Deveight House Blaris . in Lisburn; death of Dr Emerson Wilson Henry , brother of W. Tennent Henry 10 Dec 1881 DR
then I found in Ros Davies Co Down website this is her message board
http://freepages.genealogy.rootsweb.ancestry.com/~rosdavies/WORDS/RollCall.htm#DJames DEVITT ? of Devitt Hall, Co. Down; father of Rev. Clotworthy Devitt Esq. of the General Post Office , Dublin, married Jane Buck the only daughter of Andrew Buck
Esq. eminent Attorney of this City(Dublin) terry.murfitt ' at ' virginmedia.com
Genes Reunited has birth index for tree holders entries, you join to contact tree holders
James Devitt 1810 Unk ... No Elizabeth Find out more
James Devitt 1800 Ireland ... No Anthony Find out more
James Devitt 1799 Ireland ... No Andrew Find out more
James Devitt 1795 Ireland ... No Steve Find out more
James Devitt 1790 Ireland ... No Victoria Find out more
James Devitt 1788 Doolan, Clare, Irela... No Arthur Find out more
James Devitt 1788 Co Clare, Ireland ... No Paul Find out more
James Devitt 1760 Ireland ? ... No Paul Find out more
I didnt give up and tried again searching for Devitt in Ulster 1790 +or- 50 years
William Devitt 1820 Belfast County Antri... No David Find out more
Clotworthy Devitt 1787 Antrim County Antrim... No Paul Find out more
I need to stop now
keep going