A replica of a manned balloon like the ones used in the Civil War for reconnaissance is scheduled for liftoff on July 4 from a museum near Rochester, N.Y. — but only if an adequate supply of helium can be found.

It turns out helium is hard to find because of the 1996 Helium Privatization Act that called for the government to sell off most of its reserve by 2015.

Genesee County Village & Museum president Peter Arnold made an appeal recently for helium so the museum’s $350,000 project can get off the ground. He said in a telephone interview that he had been offered assistance from staff at the Smithsonian and also from a physics laboratory in Virginia. However, he won’t know until next week if either will work out.

“All we have now is the possibility of being able to get the helium,” he said. “Other than that, we are ready to go.”

The balloon is named the Intrepid after one of the Union’s balloons used to spy on Confederate activity. The name is on one side and a giant eagle with a 35-foot wing span is painted on the other.

Arnold said the museum took on the project as a way to participate in the war’s sesquicentennial and because it was in keeping with the time period of its authentic 19th century village, the third largest collection of historic buildings in the country. For the 4th of July weekend, a Civil War encampment is planned, with the launching of the balloon as the main event.