NAHANT – The band is rehearsing the biggest dance hits and the dresses are nearing completion for the social event of the Nahant season – the 1861 season that is.”In the period, they’d do some dancing, have dinner at midnight and then dance until dawn,” said Nahant Victorian Day Ball organizer Catherine Bishop. “We don’t have the lifestyle or budget to do that. You can only do that if you don’t have to go to work the next morning and have servants to do everything at home.”But while the lifestyle for Nahanters has changed since the 1860s, the dancing – at least for one night – remains the same.This Saturday, Bishop and members of the Nahant Historical Society will recapture the town’s heyday as a summer resort by celebrating two anniversaries: the 20th anniversary of the Nahant Victorian Day Ball and the 150th anniversary of the beginning of the Civil War.The ball will be held at Town Hall from 7 to 10:30 p.m. Saturday, and all are welcome to attend to watch and participate; period dress is not necessary. A dance workshop will be held from 3 to 5 p.m. to teach the dance steps.”It seemed very appropriate to do Civil War-era this year,” Bishop said. “It’s our most popular because it’s the one that most people recognize. I think most people can picture Scarlett O’Hara and Gone With the Wind.”But because this is Nahant the band Spare Parts will play such Nahant-specific favorites as the “Nahant Waltz,” “The Nahant Polka,” “The Sea Serpent Polka” and the “Nahant Quadrille.”All reflect the prominence of the town in the first half of the nineteenth century, Bishop said, as Bostonians escaped the city heat by traveling to private homes or to the Nahant Hotel on East Point.”People in New York had Newport; people in Boston had Nahant,” Catherine Bishop’s husband Ben said.A lifelong resident of the town, Bishop said that she had been interested in the Victorian Era since about the age of 12. She became particularly interested in the historical dresses of the period, studying costume design and history and working in textile conservation at the Boston Museum of Fine Arts.She attended her first period dance about 22 years ago, she said, and instantly got a shot of confidence.”I was always too shy to dance until I was wearing the clothing and a friend invited me to a ball,” Bishop said. “Maybe I felt I wasn’t myself, but it made me not feel embarrassed [to dance].She also said that the Victorian clothing fit her narrow, sloping shoulders and curvy but diminutive frame “like a dream.””Corsets are surprisingly comfortable,” she said. “Contrary to what you hear in every Victorian movie ever n they aren’t worn that tight, and they give you extraordinary posture. You can slouch and nobody notices.”And Scarlett’s quest for a 20-inch waist. Husband Ben Bishop helps with the corset, but never pulls it that tight.Fashion magazines “had their own version of Photoshop” in the past,” he said.”Most of the images are doctored,” he said.Over the past twenty years, the Bishops have become regulars on the period dance circuit. They dance locally with the Commonwealth Vintage Dancers, and have even been filmed for episodes of the PBS series “The American Experience.”Even their twin 14-year-old sons Nick and David take part, the Bishops said, evening out the male-to-female ratio for contra dances.Catherine Bishop also established a period-dressmaking business called Vintage Victorian to create dresses for fellow period dancers.She said she scours flea markets and yard sales to collect clothing and fabrics from the 19th and early 20th century, and researches historical documents and contemporary fashion magazines to recreate dresses, petticoats, corsets, stockings and other period clothing and accessories. An average Victorian dress costs between $300 and $500 she said.”I like to escape to the past and forget all the drama of the economy, kids ?,” she said.Not that the past didn’t have its own moments of stress for a well-dressed lady. That’s where Ben Bishop