"Lifting a baby hippopotamus" story

When I was a kid I read a story about a man who went to see the circus at a time when one of the circus’s hippopotamuses gave birth. The baby hippopotamus was so tiny that the man was able to lift it easily.

The man was intrigued by the idea that, since a hippo doesn’t grow much from one day to the next, if he lifted the baby hippo every day he’d still be able to lift it when it was full-grown.

So he took a job with the circus and left town with it, and continued his regimen of lifting the baby hippo daily.

At the end of the story he lost his glasses, tried to lift the mother hippo by mistake, and had a heart attack from the strain of it. As he lay dying in the straw of the hippo pen, he wondered out loud, “I wonder how much a blue whale weighs when it’s born?”

I can’t remember the title or author of this story, but I’d love to set my eyes on it again. Some help?