From the 1997 book The Great Kettles: A Tale of Time page 22.

Catch a ride with the Sandman on The Great Kettles' official taxi: the Checker Cab! Along the way, you might see Father Time, Mother Nature, Professor Throttleman or any of the hundreds of colorful characters from the land where imagination makes anything - and everything - possible. (Each piece is sequentially numbered in an old-fashioned meter in the border of this unique print.) - Dean Morrissey