Reserved, erudite, professorial describes William Gurstelle, 55, along with polite and soft-spoken. So how could he ever have written a book with such an explosive title? The Practical Pyromaniac: Build Fire Tornadoes, One-Candlepower Engines, Great Balls of Fire, and More Incendiary Devices, his latest on blowing things up, comes out from Chicago Review Press.

In The Practical Pyromaniac, Gurstelle describes 25 pyrotechnic experiments using common items easily found around the house or bought at any hardware store. Not only does he outline each step of each project in painstaking detail—complete with photos and diagrams—but he also recounts the accomplishments of 18th- and 19th-century scientists who have inspired him to replicate their experiments with fire. This is a DIY book for geeks who like to set science projects in their proper historical context.

To explain why he wrote The Practical Pyromaniac, Gurstelle suggests a walk downtown to ask 10 passersby to define fire. "You'd get 10 different answers," he says. "By playing with fire in a wise and responsible way, you really get to understand what the phenomenon is."

Gurstelle has always been interested in "highly kinetic science." The son of a pharmacist, the St. Paul, Minn., native recalls, as a youth, owning a chemistry set and making things that he could then blow up, "for my own entertainment." It's still something that he obviously enjoys, though he stresses that he practices safe, responsible, and genuine science.

"It's not about making bombs, or causing destruction," he emphasizes. "[The experiments] have been vetted carefully, to make sure they're safe, even the flame throwing," he adds, without a hint of irony.

An affection for scientific tinkering led Gurstelle to the University of Wisconsin at Madison and a B.S. in mechanical engineering in 1978. After receiving his M.B.A., he worked for several years as a billing analyst for "the phone company." But his passion lay in conducting experiments and building devices in his spare time—like potato cannons fueled by hairspray.

Wanting to "massage my ego, to feel good about myself," Gurstelle decided to share his favorite projects with the world. His first book, Backyard Ballistics: Build Potato Cannons, Paper Match Rockets, Cincinnati Fire Kites, Tennis Ball Mortars, and More Dynamite Devices, was published by Chicago Review Press in 2001 and has since sold 300,000 copies.

"Once my book took off, I never looked back," he says. "Now I write full-time. Sometimes I feel like I'm the luckiest guy in the world." Gurstelle's publications mashing up science, history, and DIY include Absinthe and Flamethrowers; The Art of the Catapult; Building Bots; Whoosh, Boom, Splat; and Notes from the Technology Underground. He's also a contributing editor at Make and Popular Mechanics magazines.

Back at his laboratory in a quiet residential area of Minneapolis, the "Barrage Garage," a 12-ft.×20-ft. freestanding structure between his backyard and the alley, Gurstelle's daredevil side emerges. Demonstrating his "Tornado of Fire" experiment, created using a modified sped-up record turntable, aluminum wire, and cloth that's been soaked in kerosene and crammed inside an old ceramic teacup, Gurstelle exclaims, as thrilled as if this were his first time, "Look at the flame! See how the tongue of fire is growing!" He explains excitedly precisely why the flame twists and twirls as it shoots up into the air. It is, frankly, fascinating, both the transformation in Gurstelle's demeanor and the fire's vortex. Urged on, Gurstelle repeats the experiment, before moving on to the much tamer "One-Candlepower Engine": a candle pierced with a pin and placed between two boxes of Morton's salt. As the lit candle seesaws, Gurstelle explains the physics behind this experiment as well.

Suddenly Gurstelle's wife, Karen Hansen, a writer and musician who plays clarinet with the Rochester, Minn., symphony, appears and announces that there's just been a terrible natural gas explosion a mile away; the resulting fire has shut down the freeway and some streets nearby. While Gurstelle, who clearly has an alibi, suggests alternate routes out of the neighborhood, Hansen's advice is more succinct: "If you see flames, drive the other way!"