In pictures: The old-timey fun of vintage baseball

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  Vintage baseball player Matt Fischetti with the Resolute Base Ball Club of Elizabeth, New Jersey, waits for his turn to bat during the 2014 Base-Ball Exhibition & Fair at the Navy Yard in Philadelphia. The clubs play baseball according to rules of the game as it was played in 1864. Matt Rourke / AP

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  They pitch underhand. No one is using a batting helmet, fielding glove or catcher's mask. And there is a plethora of floppy hats and groomed mustaches, in the style of baseball's mid-19th century beginnings. Matt Rourke / AP

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  Alex and Sherri Groff of Oaklyn, New Jersey, watch a vintage baseball game during the 2014 Base-Ball Exhibition & Fair at the Navy Yard in Philadelphia. Matt Rourke / AP

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  According the baseball rules of 1864, frequent phrases from the umpire, sometimes called the arbiter, include “Tally!” as a runner scores and “The striker is dead!” when a batter makes an out. Joseph Kaczmarek / AP

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  These vintage clubs are part of a growing trend that includes teams across the US recreating the 19th century through historically accurate uniforms, period rules and cheeky nicknames. And by spelling "baseball" as two words. Matt Rourke / AP

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  "It brings people back to a simpler time, before million-dollar contracts, TVs, cars, steroids and gloves," says Mid-Atlantic Vintage Base Ball League commissioner Bruce "Early" Leith of vintage baseball's appeal. Joseph Kaczmarek / AP

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  The Mid-Atlantic league includes about 20 squads from Rhode Island to Virginia and plays by what are called the 1864 rules. Leith (unseen) also serves as president of the Eclipse Base Ball Club of Elkton, Maryland. Eight years ago, he said, there were only three teams in that area. Today, there are 14. "We get calls all the time from people wanting to start a club," he says. Matt Rourke / AP

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  Above, vintage baseball players Al "Rocky" Belbol, with the Brooklyn Eckfords of New York, left, and Jamie "Mouth" Ford, of the Athletic Base Ball Club of Philadelphia, try to get the upper hand to determine bating order during the 2014 Base-Ball Exhibition & Fair at the Navy Yard in Philadelphia. Matt Rourke / AP

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  Baseball mythology has long held the game was invented in 1839 by Abner Doubleday in Cooperstown, New York. But researchers now say its regulations began to be codified in the 1840s by Alexander Cartwright and the Knickerbocker Base Ball Club of New York City. Those bylaws were frequently revised, giving today's vintage teams a variety of old rulebooks to choose from. Matt Rourke / AP

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  One of the biggest differences between baseball in 1864 and modern baseball is that fielders could catch a batted ball on one bounce to make an out - an understandable accommodation for players trying to handle a hard ball without gloves. Such equipment didn't become common until later. Joseph Kaczmarek / AP

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  The Athletic club sets a high standard for historical accuracy during its weekly games. Their wool uniforms, which cost about $300, include mother-of-pearl buttons, a bow tie and newsboy cap. Home plate is a white disc and the bases are sand-filled canvas bags. Matt Rourke / AP

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  "We try to do everything we can as close as possible to the period," Alberts said. "Because if we're not doing that, we might as well just be playing softball in the park," says Alberts (unseen). Matt Rourke / AP

Images from the 2014 Base-Ball Exhibition & Fair in Philadelphia, where vintage baseball teams – playing by the rules of the game from 1864 – converged to compete against one another and celebrate baseball’s history.