The newly discovered notes were purchased by executives of The Bronte Society at Sotheby's auction house in London on Wednesday (12Dec12).
The six letters, written between 1832 and 1853, will now be returned to the Bronte sisters' former home in Haworth, northern England, which houses a museum dedicated to the works of the literary family.
Ann Dinsdale, collections manager at the museum, says, ""These are amongst the most significant Bronte letters to come to light in decades.
""They belong in Haworth and we are delighted that both scholars and members of the public will now have the opportunity to study and enjoy them, either here at the Bronte Parsonage Museum, or through our online resources.""
An unpublished manuscript by Bronte went under the hammer for $1.1 million (£690,850) last year (11).