If you thought we were finshed with arguing about whether Ronald Reagan is our 39th or 40th president, you are hereby granted unanimous consent to revise and extend your thinking.

Joseph Preble Weeks of Hhartwood, Va., says the tally went haywire between James K. Polk (our 11th president) and Zachary Taylor (who is usually considered to have been our 12th).

Weeks says, "Scheduled to succeed Polk at noon on 4 March, 1849, Taylor refused to violate the Sabbath by taking the oath on Sunday. As president pro tempore of the Senate, Sen. David Rice Atchison of Missouri automatically became president. Mr. Atchison even appointed several old cronies to Cabinet positions. Then he had a few drinks and went to bed until Taylor took over the reins of government at noon on Monday."

Our ever-resourceful Washington Post library had no trouble confirming the facts that Weeks cited. Atchison was elected president pro tem of the Senate 16 times, and Scribner's Dictionary of American Biography says of him: "By virtue of this position, it has been asserted that Atchison became president for one day when the 4th of March, 1849, fell on a Sunday and Zachary Taylor did not take the oath of office until the day following. But this has been shown to be without substantial foundation (G. H. Haynes, American Historical Review, XXX, 308-310)."

I am easily intimated, especially by triple-X historical reviews. Besides, the debate over counting presidents has almost put me down for the count, so I will not argue the matter.

However, I do wish a Scribner editor had included a footnote to explain why a man who was, under the Constitution, president for a day is not counted as one of our presidents.

I agree with District Liner Weeks that Atchison's administration was a success. Atchison presided over one of the most tranquil periods in American history. No hint of scandal blemished his service, no program he espoused was a failure and not one columnist attacked him during his entire tenure.

In fact, Atchison may have been the best president we ever had, even if he did sleep through most of his term.

If you want to call Ronald Reagan our 40th president, it is far more logical to arrive at that total by counting Atchison once than by counting Grover Cleveland twice.