Susy’s biography came to an end that summer after starting to record a visit which they all made to Keokuk to see Grandma Clemens.  They went by way of the Lakes and down the Mississippi from St. Paul.  A pleasant incident happened that first evening on the river.  Soon after nightfall they entered a shoal crossing.  Clemens, standing alone on the hurricane-deck, heard the big bell forward boom out the call for leads.  Then came the leadsman’s long-drawn chant, once so familiar, the monotonous repeating in river parlance of the depths of water.  Presently the lead had found that depth of water signified by his nom de plume and the call of “Mark Twain, Mark Twain” floated up to him like a summons from the past.  All at once a little figure came running down the deck, and Clara confronted him, reprovingly: 

“Papa,” she said, “I have hunted all over the boat for you.  Don’t you know they are calling for you?”

They remained in Keokuk a week, and Susy starts to tell something of their visit there.  She begins: 

“We have arrived in Keokuk after a very pleasant——­”

The sentence remains unfinished.  We cannot know what was the interruption or what new interest kept her from her task.  We can only regret that the loving little hand did not continue its pleasant history.  Years later, when Susy had passed from among the things we know, her father, commenting, said: 

When I look at the arrested sentence that ends the little book it seems as if the hand that traced it cannot be far—­it is gone for a moment only, and will come again and finish it.  But that is a dream; a creature of the heart, not of the mind—­a feeling, a longing, not a mental product; the same that lured Aaron Burr, old, gray, forlorn, forsaken, to the pier day after day, week after week, there to stand in the gloom and the chill of the dawn, gazing seaward through veiling mists and sleet and snow for the ship which he knew was gone down, the ship that bore all his treasure—­his daughter.