The Northern Lighthouse Trust said it can conserve its lighthouse collection better if it sells other books to raise cash
Part of a rare library of historic travel books including ones owned by Captain Cook is being sold off to try to protect the rest of the collection.
The Northern Lighthouse Heritage Trust owns documents of voyages by 18th and 19th Century explorers such as Captain Cook and Matthew Flinders.
The trust says the money raised will help safeguard the treasures which remain in its collection.
The collection is estimated to sell for £200,000 in Edinburgh next Wednesday.
The books on sale include records of great journeys such as James Bruce's exploration of the River Nile and Captain Cook's voyages in the Pacific.
There is a 19th Century Matthew Flinders atlas of Australia which was delayed in publication because the explorer was jailed for six years on his way home.
The Northern Lighthouse Heritage Trust, which is based in Edinburgh, said it had decided to sell the books to raise money to conserve other items in its collection such as Robert Stevenson's account of the Bell Rock light and keepers log books from the days when lights were manual.
Auctioneers Lyon and Turnbull said it was a rare honour to sell such a large collection of "wonderful books in superb condition".
Peter Mackay, a trustee of the Northern Lighthouse Heritage Trust, said they had taken the difficult decision to sell off some items from their library.
He said: "We feel that about a third of the books are core lighthouse books and the other two thirds are much more general 19th Century Victorian travel and history.
"We need to conserve our lighthouse books better and we can only do that if we have money, which we can best get by selling off the non lighthouse books."
The Northern Lighthouse Board receives no government money and is funded by fees paid by commercial ships and large fishing boats which call in at British ports.
About 200 books are to be sold at auction.