"Harper is the only person we have recorded who actually knew Douglas," Mr Watson said.
Mr Watson said when the book Mr Explorer Douglas, by John Pascoe, was revised by Graham Langton, they had to go to the Alexander Turnbull to consult Douglas's original records.
However, it turned out the former Westland Savings Bank had ended up with some of his collection. Former Westland mayor Durham Havill negotiated for it to go to Hokitika, and it has since been scanned and digitised.
"There are wonderful drawings of mountain scenes."
Douglas' field diaries have also been digitised. Some will be presented over the celebratory weekend, and others exhibited.
Hokitika Museum curator Julie Bradshaw recently re-examined an old mineral collection, and found the writing was the same as Douglas'. Museum staff also found the associated maps, so they now know where he found the minerals.
Until then, the collection had been a "bit of a puzzle".
"It's really exciting ... they've uncovered something really interesting and really valuable."
Mr Watson said roll maps would also be on display. They went missing for a while, until someone walked into a talk in Lower Hutt with some under his arm in the 1970s. Author Pascoe then put them in the National Archives but they were not well referenced and could not be found.
Celebratory events planned include guided walks, an exhibition, illustrated talks at the Hokitika Regent Theatre, performances and a launch and reprint of the revised edition of Mr Explorer Douglas.
- Greymouth Star
