Gone are the old, 100-watt incandescent bulbs. In their place are the corkscrew-shaped compact fluorescent light bulbs that are all the rage for their energy efficiency. Each burns just 23 watts of power and shines just as bright as the old bulbs.

"I'm just trying not to think of where I am as I'm doing this," said parishioner Kirsten Chapman as she stood on a narrow platform to replace the bulbs.

A look down revealed a drop of several stories to the bottom.

At $3 each, the compact fluorescent bulbs are a small but symbolic contribution that St. Anne's is making to greater environmental awareness and energy efficiency in the city of Annapolis, officials said.

Although the 4-foot-wide clocks are part of the Episcopal church's building, the clocks and their bulbs technically belong to the city government, said the Rev. Bob Wickizer, acting rector.

The current church building is the third for St. Anne's and was built in the mid-1800s.

The Rev. Wickizer said no one knows for sure why or when exactly the clocks were installed, though they are marked with the year 1927.

"I presume sometime around that era, the city decided the public needed to know the time of day," the Rev. Wickizer said.

Normally, the city handles maintenance of the clocks, but St. Anne's got permission to put in the new light bulbs as a way to mark Earth Day.

There was only one hitch in the plans, though: once the intrepid environmentalists got to the top, they realized 16 bulbs were needed, and they only brought eight.

So, soon there will be another expedition up narrow passageways to make a small difference for the Earth.