Where is the irony in Mark Twain's "The Celebrated Jumping Frog of Calaveras County"?

This hilarious story by Mark Twain is perhaps one of the
most famous literary examples of a tall tale, which can be defined as a humorous story
characterised by outrageous exaggeration and outlandish events. Given this definition,
and the nature of the tale, relating the story of Jim Smiley who apparently has a
god-given ability to bet correctly every time and how he receives his comeuppance, irony
plays a central role in the humour of this tale.

However,
central to what makes something funny or not is not the content, but the way in which
the story is told, and this is demonstrated in this short story through the tone that is
adopted. It is the tone that is used and how it stands in contrast to the events
narrated that makes the use of irony so successful. Wheeler, the narrator of the tale
within a tale, tells his story throughout with a calm and serious tone. Consider the
following passage where Wheeler tells about Smiley's
dog:

Smiley
always come out winner on that pup, till he harnessed a dog once that didn't have no
hind legs, because they'd been sawed off by a circular saw, and when the thing had gone
along far enough, and the money was all up, and he comes to make a snatch for his pet
holt, he saw in a minute how he'd been imposed on and how the other dog had him in the
door, so to speak, and he 'peared surprised, and then he looked sorter discouraged-like,
and didn't try no more to win the fight, and so he got shucked out
bad.

There is immense irony
employed in the description of the fight, but also this displays the tone of Wheeler and
how humour is created. This story demonstrates that the disparity between the serious,
calm tone employed and the absurdity of the tale is what makes this tale so ironically
funny.