ELKTON - A New York manuscript expert needed all of 30 seconds yesterday to declare that a letter found in a Cecil County historic home, purportedly written by Thomas Jefferson, is indeed authentic and worth $700,000.

"Essentially, I knew it at a glance," said Chris Coover, who works at Christie's auction house in New York. He pointed out the paper's watermark from J. Whatman, the finest English writing paper of the time, and the distinctive Jefferson script.

"The handwriting is unmistakable," Coover said.

Jefferson's letter size and form were distinctive, he said, as was his tendency to pen the body of the letter in one script and his signature in another.

Members of the Historic Elk Landing Foundation - the group that bought the Elk Landing plantation, its two-story white clapboard home called Hollingsworth House, and all of the house's contents about three years ago - said yesterday that hearing the big numbers attached to the letter feels a little like hitting the lottery.

"It just opens up a whole realm of possibilities that we never anticipated," said Michael L. Dixon, president of the foundation.

Several months ago, the foundation was trying to spread the word about its goal to develop a living history park at Elk Landing, the name given to a plantation bought by merchant Zebulon Hollingsworth in 1735. Today, members are holding news conferences and fielding calls from national scholars.

"The finding of this letter doesn't keep us local anymore - we're international, worldwide," said foundation board member Jack Beaston.

The letter is not for sale, board members said yesterday. But the group will meet next week to talk about what to do with it. The letter could be lent for a fee, for example, to museums or to the Library of Congress, they said.

"I'm sure it will take them a while to figure it out," said Jefferson scholar Barbara Oberg. She said she is "delighted it is authentic" and glad the letter will not be sold.

"I like for things to be available to people, not just scholars, but for the public to see," she said. "Schoolchildren get very excited when they see an actual letter in someone's writing like Thomas Jefferson's. It brings history alive for them."

Oberg, a Princeton University history professor and general editor of The Papers of Thomas Jefferson, is well-acquainted with the 1801 letter. A "press copy," made while the ink was drying, is kept in Jefferson's letters at the Library of Congress in Washington. And Jefferson made note of the correspondence in his meticulous Summary of Letters, which documents the 15,000 to 20,000 letters written by the author of the Declaration of Independence.

Coover said that appraising historical documents is tricky work. In 2000, a Jefferson letter of comparable content sold for $721,000. "The content of this one is really quite exceptional," he said.

Jefferson's letter, a page-long response to a congratulatory letter from the Delaware Baptist Association, was written in July 1801, just months after he was elected the third president of the United States in a disputed victory over Aaron Burr.

The letter firmly supports religious freedom and the need to separate church and state. "It alludes to both of those and alludes to those freedoms as part of the heritage of the [American] Revolution," Coover said.

Oberg said authentic Jefferson letters turn up "about a dozen times a year, more than you would think," but the "fabulous content" of this letter sets it apart.

The content is only part of the fascination for Edward C. Papenfuse, Maryland's state archivist.

On a visit to Elkton, he was looking at the Baptist association's letter and Jefferson's response when something on the back of the association's letter caught his eye: "To The Mirror" was written on it - a Wilmington newspaper edited by James Wilson. A descendant of James Wilson likely married a descendant of Zebulon Hollingsworth, though how the letter got to Elk Landing remains a mystery, Dixon said.

Papenfuse began a little detective work and discovered that both letters were published in the Mirror on Sept. 9, 1801, and again in October in the New London Bee in Connecticut. Papenfuse expects that this was no coincidence.

"I think he intended this letter for publication," he said. "What it begins to show you is how the president of the United States communicated his ideas to the general public through the newspapers - friendly editors willing to pick it up and print it."

He also said Jefferson's mentions of the Revolution likely transcended the war to promote some of the ideals the young country was founded on. The 1800 election was the first time some states extended suffrage beyond property owners to all white males 18 or older - an idea that was revolutionary in the early 19th century, Papenfuse said.

Yesterday on Elkton's Main Street - officially known as Route 7, which traces one of the earliest roads in Colonial America - Main Street Cafe owner T.C. Hook said the letter has created a buzz among his regular customers. Each time a new article or television report comes out about the find, Hook said, "that's all they talk about all day."

For Joanna Alford, the volunteer who discovered the letter in March while rummaging through a box of old papers found in an upstairs bedroom of Hollingsworth House, the news of the letter's value was stunning. "Right now, I am more nervous about this letter. ... I have actually touched it," she said, laughing.

Jeanne Minner, the town's director of planning, watched a news conference about the letter yesterday with wonder. "I'm blown away," she said.

Minner had persuaded the Elkton mayor and town commissioners - who organized the Historic Elk Landing Foundation - to buy the 42-acre Elk Landing parcel for about $342,000 after she saw it on an aerial map about three years ago. "I thought it would make great parkland, actually."

She said she had no idea of the property's historical value until she talked with Dixon. "He opened up my eyes to a whole different aspect of the property."

She said her role in the events made her feel "pleased and very proud. ... I think there's a lot of museums that would have liked to have had our luck," she said, smiling.

"It definitely feels like the lottery," she said.