"A lucky miner in South America" joke

I found this inside a old business card from
Stateside Locker Club, San Diego, CA:
In a South American mining district Mrs. Brown presented her
husband with a 12 pound baby boy. Mr. Brown was so delighted that he
went to the News office and told that he had found a 12 pound nugget of
gold as good as any to be found in South America. The paper, naturally,
sent a reporter to get particulars. This is what happened:
Reporter-Does Mr. Brown live here?
Mrs.Brown- he does.
Reporter-Is he in?
Mrs.Brown-No he isn't.
Reporter-I understand he found a nugget of gold weighing 12 pounds.
Mrs.Brown-(Seeing the joke) Yes.
Reporter-Can you show me the exact location where it was found?
Mrs.Brown-I'm afraid Mr. Brown would object as it is private.
Reporter-Is the hole far from here?
Mrs.Brown-No, it is quite handy.
Reporter-Has Mr. Brown been working the claim long?
Mrs.Brown-Almost ten months.
Reporter-Was Mr. Brown the first to work it?
Mrs.Brown-He thought he was.
Reporter-Was the work difficult?
Mrs.Brown-It was at first but easier after the shaft opened.
Reporter-Is the water plentiful?
Mrs.Brown-Yes, sufficient to carry on the work.
Reporter-Has he gotten to the bottom yet?
Mrs.Brown-No, but quite near it.
Reporter-Do you think there are any more nuggets?
Mrs.Brown-Yes, if the claim is properly worked.
Reporter-Has he worked it since he found the nugget?
Mrs.Brown-No, but I told him it was time to start.
Reporter-Do you help him?
Mrs.Brown-I do my level best.
Reporter-do you think he will sell the claim?
Mrs.Brown-No, he finds too much pleasure in working it himself.
Reporter-Can I see the nugget?
Mrs.Brown-Certainly.
She brought the baby in for inspection. The embarrassed reporter
departed very fast.