on the family search site:- http://familysearch.org
Catherine Pinkerton married apr-jun 1879, Volume No. 2, Page 329, Digital folder 4179386, Robert Anderson has the same Digital folder 4179386
have a look on the Donegal Rescources site:
http://freepages.genealogy.rootsweb.ancestry.com/~donegal
type in the Basic search box, Pinkerton 
under heading_ First Raphoe Presbyterin Church, Raphoe Parish, Financial statement 1867-pew holders and stipend payers,
Alexendar, John Pinkerton and John Pinkerton Sen mentioned.
Their is also a Rev Alexandar Pinkerton mentioned,
Mr Alexander Pinkerton of Ramelton
Rev. Alexander Pinkerton had a residence in Carndonagh in Inishowen in the 1840s - 1860s. He is recorded as the Presbyterian minister at various marriages in the area at that time. His daughter was Bessie Cunningham Pinkerton, who was born c. 1863, lived in Carndonagh and died aged 13 in Belfast (Sydenham) on 9th January 1876.