(Image courtesy of Therese Oneill)

Oneill's tongue-in-cheek guide offers tips for the modern woman time-traveling back to the 19th Century.

If you’re a fan of the Victorian era, maybe you love it for the poetic language or sweeping dresses. But when making a film like "Gone With The Wind," filmmakers didn’t have to answer the tough questions about the 19th century.

Like, how did they manage to tolerate dancing so closely when bathing was more of a special occasion than a routine? And if one had to pause for a moment to go use the facilities, where did one go when indoor plumbing was not yet mainstream? And how did one do that in a Victorian dress for that matter?

A 21st-century writer named Therese Oneill decided to answer those questions and more. Her new book is "Unmentionable: A Victorian Lady’s Guide to Sex, Marriage and Manners."

The book is filled with helpful tips for any woman looking to travel back to the height of the Victorian era. These include:

1. All underwear is crotchless until the 20th Century.

2. Don’t impudently withhold your menstrual blood or else you’re gonna get consumption.

3. Bathing can kill you.

It’s satire — and it’s satire laid on very thick. But while it may sound ridiculous today, the whole book is compiled from material that was taken seriously at the time. Rigorous scientific research was, well, not so much.

“The ability to write the word “doctor” in front of your name was pretty much the only criteria for being a doctor,” Oneill said.

That and having access to a printing press to disseminate the “advice.”

“You will find a good husband. And you will know he’s a good husband by the shape of his head,” Oneill advised.

The nearly 300 pages in Oneill’s guide is the result of a jump down a long and winding rabbit hole. And it started with Scarlett O’Hara’s dress.

“There’s this scene where Scarlett early in the movie is running across Tara to see her father,” Oneill said. “And she’s lifting up these huge bell-curve wire crinoline.”

That’s the literal cage under her dress to keep that bell shape.

“You know, the circumference of which is this room. And it just dawns on me — how in the world did she fit that into an outhouse?”

Oneill added it’s not that she wants to ruin the romantic image of the era by discussing chamber pots ad nauseum. She wanted to learn about the hard reality that was the real Victorian era, something she said is forgotten in the movies.

“I like to look into the dark corners to find the stuff that we forgot and got stomped on and smooshed or dusty,” Oneill said. “I spit shine it, I hold it up and I say, ‘Holy cow guys, look what I found.’ I didn’t want the grime and the grit so much, that’s what happens — but I wanted the humanity underneath it.

And after the laughs about bust cream and handkerchief flirtations, Oneill found something — in all seriousness — to admire about the time.

“The fortitude of women. How much they can take, and do. And how far they can go after they’re tired,” she said. “Because they were tired. And they kept going.”

As Scarlett says, “After all, tomorrow is another day.”

Therese Oneill will be talking about her book at Phoenix’s own Victorian-era Rosson House on Thursday night.