Tithe was a tax on all agricultural land (originally one tenth of the produce) excepting only church lands, glebes and urban areas and was paid by leaseholders and occupiers of all religious denominations to the clergy of the Established Church of Ireland. There was growing resentment against this tax, especially by Presbyterians and Catholics, particularly in the period of distress after 1815 and the government was forced to give way and introduce the Tithe Composition Act 1823 which replaced payment in kind by payment in cash.
In order to effect this change, all agricultural land across the country was required to be surveyed and applotted, or valued. During the period 1823 to 1837, a Tithe Applotment Survey was made in each civil parish across the whole of Ireland to determine the value of tithe payable by different landholders. Two people were appointed by each parish to carry out this assessment. The material was arranged by civil parish and townland in volumes known as TITHE APPLOTMENT BOOKS.
In some parishes more than one survey was taken, whilst in others the manuscript has not survived. The books for all Ireland, compiled between 1823 and 1837, are now deposited in the National Archives of Ireland, Dublin and Public Record Office of Northern Ireland (PRONI).
PRONI holds the tithe books for all but 31 of the 273 parishes then surveyed in Northern Ireland. These tithe books are arranged by townland and record the names of leaseholders, the area of their farm subject to tithing, sometimes the quality of the land and an overall valuation and occasionally, the names of landlords. Researchers should be aware that cottiers who did not hold land are not recorded, and unaccountably, some types of land were passed over entirely; a field of potatoes attracted a tithe payment in one parish, but not in that adjoining.
Those researchers who are fortunate to locate a forebear in the Tithe Applotment Books may find it possible to take their research back a further generation prior to Griffiths Valuation.
N.B. - Errigal Trough parish straddles the Tyrone-Monaghan county boundary with twelve townlands located in Co. Tyrone
OFFICIAL ERRIGAL TROUGH TOWNLANDS WITHIN CO. TYRONE
| Townland | Townland | Townland | Townland | Townland |
| Altadaven | Cullamore | Dernasell | Derryclay | Derrycloony |
| Drumadarragh | Durless Black | Durless White | Edenmore | Favor Royal Demesne |
| Fymore Mourtray | Fymore Todd | Gallagh | Killaveny |
TOWNLANDS AND SUBDENOMINATIONS WITHIN CO. TYRONE SUBJECT TO TITHING RECORDED IN THE TITHE APPLOTMENT BOOK (AS SPELT)
| Townland | Townland | Townland | Townland | Townland |
| Altadavin | Carrickavoy | Cullamore | Dernadaragh | Dernasell |
| Derryclay | Derrycloony | Durlis Black | Durlis White | Edinmore |
| Fighmore | Gallagh | Killavney | Killybrick | Killycarnan |
THE 1826 ERRIGAL TROUGH TITHE APPLOTMENT BOOK
***ORIGINAL SPELLING HAS BEEN RETAINED***
| SURNAME | GIVEN NAME | TOWNLAND |
| ANKETELL | Roger, Esq. | Cullamore |
| ANKETELL | Wm., Esq. | Cullamore |
| BANE | William | Dernadaragh |
| BELL | Jo. | Dernadaragh |
| BUNBERRY | Captn. | Derryclay |
| BURKE | James | Durlis Black |
| BURKE | Patt. | Killavney |
| BUSBY | Henry | Dernadaragh |
| CAMPBELL | John | Killybrick |
| CASSIDY | Francis | Killavney |
| CASSIDY | Owen | Fighmore |
| CASSIDY | Patt. | Killavney |
| CLIFFORD | John | Derryclay |
| CLIFFORD | Robt. | Derryclay |
| COLWELL | James | Fighmore |
| CONLAN | James | Fighmore |
| CONLAN | John | Dernadaragh |
| CONLY | Francis | Durlis White |
| CONLY | James | Durlis White |
| CONLY | Pat. (Tom) | Dernasell |
| CONOLLY | John | Altadavin |
| CONOLLY | Patt. | Dernasell |
| CULLIGAN | Patt. | Killycarnan |
| CURRAN | John | Derryclay |
| CURREN | Thomas | Derryclay |
| CURREN | Thomas | Gallagh |
| DOLIN | John | Dernadaragh |
| DONELLY | Edward | Killybrick |
| DONELLY | Peter | Altadavin |
| DONLY | James | Altadavin |
| DONLY | Michl. | Altadavin |
| FARLEY | Patt. | Dernadaragh |
| FERRY | Barny (Hugh) | Derrycloony |
| FRYARS | William | Fighmore |
| GLENEY | James | Fighmore |
| GRAHAM | Arthur | Dernadaragh |
| GRAHAM | Robert | Fighmore |
| HACKET | James | Fighmore |
| HACKET | John | Carrickavoy |
| HACKET | Milse | Carrickavoy |
| HAMIL | Patt | Dernadaragh |
| HOLLAND | Edwd. | Altadavin |
| HOLLAND | Hugh | Killavney |
| HOLLAND | James | Altadavin |
| HOLLAND | Michl. | Cullamore |
| HOLLAND | Patt. | Altadavin |
| HUGHES | Cormick | Killavney |
| HUGHES | Owen | Altadavin |
| HUGHES | Owen | Derrycloony |
| HUGHES | Owen | Durlis Black |
| HUGHES | Patt. | Killavney |
| HUGHES | Widow | Altadavin |
| JOHNSTONE | William | Killavney |
| KEENAN | Patt. | Derryclay |
| KEENAN | Peter | Derryclay |
| KILPATRICK | John | Gallagh |
| LITTLE | William | Dernadaragh |
| McAVICAR | Dennis | Altadavin |
| McAVICAR | John | Altadavin |
| McAVICAR | John | Durlis White |
| McAVICAR | Owen | Altadavin |
| McAVICAR | Peter | Durlis White |
| McAVICAR | Thomas (deleted) | Durlis Black |
| McAVICAR | Widow | Altadavin |
| McAVICAR | Widow | Durlis White |
| McCANN | Francis | Killavney |
| McCANN | James | Altadavin |
| McCANN | Michael | Dernadaragh |
| McCANN | Michl. | Derryclay |
| McCANN | Owen | Gallagh |
| McCANN | Patt. | Fighmore |
| McCANN | Patt. | Killavney |
| McCANN | Peter | Gallagh |
| McCARNEY | Owen | Killybrick |
| McCARRON | Francis | Altadavin |
| McCARRON | James | Dernadaragh |
| McCLELLAN | John | Fighmore |
| McCOWEL | Barny | Dernadaragh |
| McCOWELL | Widow | Killybrick |
| McCUSKER | Barny | Dernadaragh |
| McCUSKER | Bernard | Gallagh |
| McCUSKER | Dominick | Killybrick |
| McELMEEL | Hugh | Derrycloony |
| McELMEEL | James | Derryclay |
| McELMEEL | James | Derrycloony |
| McELMEEL | Michl. | Derrycloony |
| McELROY | Owen | Edinmore |
| McENANLY | Daniel | Killycarnan |
| McENANLY | James | Durlis White |
| McENANLY | Milse | Durlis White |
| McENANLY | Owen | Durlis White |
| McFARLAN | John | Dernadaragh |
| McGALE | Edward | Gallagh |
| McGARLAN | Paddy | Derrycloony |
| McGARLAN | Thomas | Derrycloony |
| McGARLAND | Francis | Dernasell |
| McGAUGY | Chas. | Derrycloony |
| McGAUGY | Daniel | Cullamore |
| McGAUGY | James | Altadavin |
| McGAUGY | James | Durlis Black |
| McGAUGY | Jas. | Derrycloony |
| McGAUGY | John | Derrycloony |
| McGAUGY | Milse | Durlis White |
| McGAUGY | Owen | Derrycloony |
| McGAUGY | Patt. | Altadavin |
| McGAUGY | Patt. | Durlis Black |
| McGAUGY | Peter | Derrycloony |
| McGAUGY | Peter | Durlis Black |
| McGAUGY | Wm. | Cullamore |
| McGINN | John | Altadavin |
| McGREGOR | Robert | Fighmore |
| McKENNA | Barny | Killavney |
| McKENNA | Francis (Faddy) | Dernasell |
| McKENNA | Francis, Senr. | Dernasell |
| McKENNA | James | Dernasell |
| McKENNA | James | Fighmore |
| McKENNA | James | Gallagh |
| McKENNA | James (Gate) | Altadavin |
| McKENNA | James Andy | Durlis White |
| McKENNA | James C. | Dernasell |
| McKENNA | John | Dernadaragh |
| McKENNA | John | Dernasell |
| McKENNA | John | Derrycloony |
| McKENNA | John | Durlis Black |
| McKENNA | John | Gallagh |
| McKENNA | John (Faddy) | Dernasell |
| McKENNA | John (Michl.) | Dernasell |
| McKENNA | Michael | Derrycloony |
| McKENNA | Michl. | Durlis Black |
| McKENNA | Owen | Cullamore |
| McKENNA | Owen | Fighmore |
| McKENNA | Patt. | Altadavin |
| McKENNA | Patt. | Cullamore |
| McKENNA | Patt. | Durlis White |
| McKENNA | Patt. | Fighmore |
| McKENNA | Patt. (Major) | Altadavin |
| McKENNA | Patt. (Roe) | Killavney |
| McKENNA | Patt., Senr. | Durlis White |
| McKENNA | Peter | Dernasell |
| McKENNA | Peter | Fighmore |
| McKENNA | Widow | Durlis White |
| McKEON | James | Derryclay |
| McWADE | Michl. | Cullamore |
| McWADE | Patrick | Derryclay |
| MOUTREY | Widow John | Durlis White |
| MULLAN | John | Dernadaragh |
| MULLRINE | Owen | Killavney |
| MULRAIN | Patt. | Derrycloony |
| POWELL | Captn. | Killycarnan |
| QUIN | John | Derrycloony |
| RAFERTY | Patt. | Altadavin |
| RAFERTY | Terence | Altadavin |
| RAFERTY | Terence | Killybrick |
| SALLY | Art. | Altadavin |
| SALLY | John | Altadavin |
| SCANLAN | Edward | Gallagh |
| SHARRY | Edward | Derrycloony |
| SHARRY | Francis | Derrycloony |
| SHARRY | Patrick (Larry) | Derrycloony |
| SHARRY | Patt. | Derrycloony |
| SHERIDAN | Bryan | Derryclay |
| SIMPSON | George | Fighmore |
| SIMPSON | Samuel | Fighmore |
| SIMTON | Patt | Derryclay |
| STEENSON | Thos. | Gallagh |
| TODD | Edward | Killavney |
| TODD | James | Fighmore |
| TODD | William | Killavney |
| WILSON | John | Derryclay |
| WINSLOW | Robert (of Longhill) | Derryclay |
| WINSLOW | Robt. | Dernadaragh |