Why should he expect gratitude?
He did not pay Clark for gratitude, but for work, and this the clerk did faithfully.

It was an ungrateful world, anyhow.
At that moment there was a light knock at the outer door, and, on Clark's bidding, some one entered.
Livingstone, from where he sat, could see the door reflected in a mirror that hung in his office.
The visitor was a little girl.

She was clad in a red jacket, and on her head was a red cap, from under which her hair pushed in a profusion of ringlets.

Her cheeks were like apples, and her whole face was glowing from the frosty air.

It was just her head that Livingstone saw first, as she poked it in and peeped around.