Dummer Twp was surveyed in 1823, when it was part of Northumberland County. Therefore
any early Dummer records are in the Northumberland Record Office, specifically the Northumberland West office
in Cobourg. It seems that these were copied when Peterborough County got its own Land Office in 1842.
When an instrument (document) was brought into the Land Office, either a copy of it was
kept or it was copied into a Copy Book. The instruments were numbered using a county-wide numbering system.
The Copy Book was, at various times, based on the county or the township. On this website the
instruments are identified by the Archives of Ontario microfilm number and the instrument number. Here
are the relevant microfilm numbers for Dummer Copy Books:
GS 4975 1833-41
GS 4976 1847-61
GS 4977 1861-68
GS 4978 1868-72
GS 4979 1872-75
GS 4980 1875-77
The 1841 to 1847 gap is covered by a Peterborough County Copy Book on microfilms GS 5056 and GS 5057.
There are also Abstract Indexes for Dummer on microfilms GSU202577 to GSU202579.
They record transactions only from the Patent.
Since no one was required to register a land transaction until 1846 and the Abstract Indexes
were created in 1865, you will realize that many early records are missing.