"What better day for the historic church to demonstrate its new exterior water curtain that can extinguish earthly fires?" asks a news release from the parish.

The new system shoots hundreds of gallons of water per minute out of the top of the historic steeple, designed to enshroud the 270-year-old building in a protective mist.

"It will be a spectacular sight," said the Rev. Timothy B. Safford, rector of Christ Church.

The demonstration will take place at 11:30 a.m. following the 10 a.m. service.

"Depending on the wind, they'll probably need umbrellas," Safford said of those who will attend the demonstration.

The day marks the completion of a year-long, $2.5 million comprehensive preservation project that brought a state-of-the-art fire suppression system to Christ Church for the first time in its history, the parish's release said.

In the Pentecost liturgy, all of the construction workers will be honored.

The 254-year-old wooden steeple has been hit by lightning countless times, but has only caught fire once, in May 1908.

"That fire was extinguished by the torrential rain at the time," Safford said, "but the time has come for more complete protection than just Ben Franklin's lightning rods."

Franklin helped design and finance the Christ Church steeple. It stood as the highest landmark -- 196 feet -- in colonial America.

The steeple also took a direct hit of lightning in June 1777, as the British Army was preparing to occupy Philadelphia.

"The only damage that time was that the crown symbolizing the King of England was melted and fell to the ground," Safford said.  "It's our favorite piece of history to tell the religious skeptics who visit."

Christ Church was founded in 1695, and the current building dates from 1727. It was the tallest building in the colonies and the United States for 75 years thereafter. When the capital was in Philadelphia, it was the Sunday meeting place for the politicians and merchants who ran the young country. An early rector, William White, later became the Episcopal Church's first Presiding Bishop and chief architect of its constitution.

During the Revolutionary Era, Christ Church welcomed the Continental Congresses. Benjamin and Deborah Franklin and Betsy Ross were parishioners. Later, George Washington and John Adams attended services while serving as the nation's presidents. Seven signers of the Declaration of Independence -- including Franklin, five signers of the Constitution, and 10 Philadelphia mayors are buried at the church.