BIDDEFORD – Floyd Hartford expects a packed house Wednesday as the Saco River Auction Co. looks to make history once again with the sale of an extremely rare baseball card.

“Everyone wants to witness a spectacle,” the auctioneer said Tuesday as he prepared for the auction of a card that may be the only one of its kind. “We don’t want to disappoint them.”

The card, with a team photo of the 1865 Brooklyn Atlantics, was found late last year by an antiques picker in Baileyville, a small town in Washington County. It initially was believed to be one of two known to exist, with the other one in the Library of Congress.

But as news of the card’s discovery and upcoming auction spread around the world, the auction house discovered the Atlantics card is even more rare than thought.

While it is similar to the card in the Library of Congress, the card at Saco River Auction Co. is printed from a different negative, said Troy Thibodeau, manager of the auction house.

He said the images on the two cards could be viewed together through a stereoscopic viewer, which created the illusion of three-dimensional depth from two-dimensional images.

The card was authenticated last month by Paul Messier, a Boston-based conservator of photos.

It’s not the first time a baseball card has drawn a crowd to the Saco River Auction Co. In August, the auction house set a Maine record for a baseball card sale when it sold a rare 1888 Michael “King” Kelly card for $72,100. That card was found by an antiques picker in a trunk full of papers from a Kennebunk estate.

The Atlantics card, which shows 10 players, is a carte de viste, a type of small photograph usually made of thin albumen print and mounted on a thicker piece of paper. Some have speculated that the card could sell for more than $100,000.

Hartford said the auction house has heard from people across the country who are interested in the card. At least six have signed up to bid by phone, and many more are expected to watch the auction online and place bids.

Thibodeau said about 3,000 bidders are expected for this month’s auction — not all of them looking for a pricey baseball card.

The auction features 425 lots, including many items that are quirky or rare.

Hartford is particularly excited to auction two campaign buttons from the four-way presidential race of 1860. One features a beardless Abraham Lincoln; the other features Stephen Douglas.

Those items are expected to draw bids of “many thousands of dollars,” Thibodeau said.

The auction will be streamed live at www.sacoriverauction.com.

Staff Writer Gillian Graham can be contacted at 791-6315 or at:

ggraham@pressherald.com

Twitter: grahamgillian