All data has been derived from the transcriptions in the IGI derived from the official 1911 transcription - thus it is a transcription of a transcription of an earlier transcription !
Based on various Church, Civil and, post 1821, Decennial Census data
The civil parish of Onchan included part of the rapidly growing North Douglas, boundary adjustments moved part of the parish to Douglas pre 1861 census, further boundary movements continued after that time. Many of those within the civil parish would have been baptised within Douglas.
The register effectively starts from 1666 though there are a few fragments from the 1620's.
Several epidemic peaks can be noted. The reason for the step function in Onchan burials around 1760 is still to be determined.
R.A. Houston The Population History of Britain and Ireland 1500-1750, Macmillan Education Studies in Economic and Social History (ISBN 0-333-56564-9) 1992