Great short read. About 70 pages.
Barnum goes on about virtues of economy, focus, advertising, getting security for endorsing loans, avoiding speculation, and general virtues that will make a person successful in business.
I made a number of highlights. Just nice short points to think about, and takes about an hour in all to read.
It's free for Kindle -- I'd recommend it. The English is a bit older which can be tricky to work through at times, but it's worth it.