Visitors are welcome to climb the tower stairs to see the bells and to talk to the carillonneur in between selections.
Many of the concerts are performed by James W. Smith, the academy's music director and organist, who took over as carillonneur when Barker retired.
It takes a great deal of skill to master the carillon, Smith says.
"A carillon is a musical instrument capable of being played with great expression, just like a piano," he says.
The bells are connected to the keyboard by a transmission system. The carillonneur has to adjust the distance from the clapper to the bell so it strikes for the right length of time, Smith says.
Six bells were added to the Swoope Carillon last October.
The 43-bell carillon didn't have enough bells to play modern literature, Smith says.
A four-octave carillon was needed, and with the additional bells, it now qualifies as a concert carillon. It is one of about 100 concert carillons in the United States.
The carillon still is missing one large bell, but the academy will get it someday, Smith says.
The renovation also included a new keyboard, as the old one made clanking noises when it was played.
Hear the history
The melodic bells also are rich in history.
The largest bell, weighing more than 3 1/2 tons, contains 223 pieces of historic copper. They include coins of Julius Caesar, Napoleon Bonaparte and Peter the Great, as well as a piece of metal from the Confederate ironclad The Merrimack, a copper bolt from Old Ironsides and a copper shaving from the Liberty Bell.
The six new bells, played for the first time Oct. 12, honor important figures in Mercersburg Academy history.
"Something was dropped in every bell as a sentimental gesture," Smith says.
Bell 44 contains the pin that carillonneur Barker won from Columbia University in recognition of his contribution to school newspapers.
Into bell 45 was dropped the Royal Air Force wings of Eric E. Harris, a science teacher at the academy for many years.
Bells 46, 47 and 48 contain personal items of the academy's headmaster, Walter H. Burgin Jr., who also was a student and teacher at the academy. Burgin's student government pin was dropped into bell 46, and a brass tobacco tamper from his teaching days when he smoked a pipe is in bell 47. Bell 48 contains a pin that was used to commemorate Black Awareness Day on the campus.
The 49th bell contains a Rotary Club pin belonging to Smith, who is active in that organization.
The carillon sounds best if you listen outside the chapel, Smith says.
Bring a lawn chair in good weather, or just roll down the window in your car.
The academy plans to install a sound system this year so the carillon can be heard from inside the chapel, Smith says.
There is no charge to hear concerts.
For information, call Smith at 1-717-328-6143.