Ebbing and Flowing Spring near Rogersville in eastern Tennessee is renowned for a rare, regular rise and fall in discharge that makes it seem to breathe. Considered one of only two known springs in the world with such tidal behavior, it cycles every 2 hours and 47 minutes, from a near trickle to about 500 gallons a minute, while staying at a constant 34 degrees Fahrenheit. The spring stood on land granted to Revolutionary War veteran Colonel Thomas Amis, who settled here around 1780, linking it to Rogersville’s earliest frontier history, Joseph Rogers, and a long-lived local legend about love and marriage.