John Henry COTTER , 1839–1922 (aged 83 years)
The entry in the NSW Deaths Index includes the details that John was 83 years old at the time of his death in 1922.
Information on how and when needs to be provided.
In the referenced Bulletin, Lyn Collingwood writes that John and Margaret were married in 1875.
The NSW Death Index entry being the correct entry is supported by the registration of the death of his wife, Margaret Hay, whose death in 1936, was also registered in Glebe.