The Brontė Parsonage in Haworth was home to the famous literary sisters
The Brontë Parsonage Museum in Haworth is "desperately" trying to raise funds to ensure Brontë treasures are not bought by private collectors.
Two auctions are to be held in December featuring Brontë-related items of a kind not seen for many years.
Andrew McCarthy, director of the Brontë Parsonage Museum, said they must be saved for the nation.
He said: "It would be very sad indeed if these treasures were not repatriated or were lost to a private collection."
On 4 December, Christie's in New York will host an auction including a number of Brontë lots, the most significant being an extremely rare first edition of Emily Brontë's only novel, Wuthering Heights.
This is the copy which was owned by her sister Charlotte, who revised the novel for a new edition after Emily's death and which contains her pencilled-in corrections.
There are also three letters from Charlotte Brontë to Henry Nussey, the brother of her close friend Ellen Nussey.
The letters include Charlotte's reflections on family, work, the relationship between men and women, and marriage.
These lots alone are expected to fetch in the region of $280,000 (£170,000) and the Brontë Parsonage Museum is attempting to raise enough money to make sure they are returned to a public collection.
Andrew McCarthy said: "There is no doubt that these are items which are of such great significance to our cultural and artistic heritage that they should certainly be thought of as national treasures."
Another auction, to be held by Sotheby's in London on 17 December, features items such as Charlotte Brontë's mahogany writing desk, a pencil drawing by Emily, and an extremely rare surviving personal possession of Emily's, her artist's box and geometry set.
Andrew McCarthy said: "It is rare for such significant items to come onto the open market.
"We feel that these are things which belong here in Haworth."