Not far from Elmira Collage, New York, is the family grave of Mark Twain's wife. In addition to the family gravestone tower, the cemetery also has a 12-foot-tall tower to commemorate Mark Twain. It turns out that the pen name of Mark Twain means -12-foot mark. When he was on a cruise in Mississippi, because the depth of the river was constantly changing, in order to ensure the smooth running of the boat, the boatman used a knotted rope to continuously measure the water level, and then the boatman reported the depth. When the boatman reported Mark Twain (water depth of 12 feet), The writer decided that Mark Twain was his pen name.