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In almost every N.B.A. and many college arenas this season, multicylinder T-shirt cannons — modeled after the Civil War-era Gatling gun — have become a regular presence during timeouts and halftime shows, partly thrilling and likewise terrifying fans as the latest weapon of mass distraction.

With their usual foresight and planning, the Wrights carefully checked and recorded the weight of each part as it was finished, but even this does not quite explain how these two individuals, inexperienced in multicylinder engines—much less in extra-light construction—could, in two months, bring through an engine which was both operable and somewhat lighter than their specification.

Pinnacle is also developing a multicylinder automotive version that software simulations show will be up to 50 percent more fuel-efficient than conventional gasoline engines, executives said.

The chief advantage of the multicylinder engine is the smoother drive obtained.