In a 10-foot-square cabin suspended by steel beams high in the tower of New York's Riverside Church, a gray-haired man is in his glory. Around him the 74 bells in the church's carillon are sounding - from the smallest, barely 10 pounds and a few inches across, to the largest, over 20 tons and as big as a baby elephant. The man, James R. Lawson, carillonneur of Riverside, is playing them all.
Seated at a carved oak clavier, an organlike instrument with shafts of wood, or ''batons,'' instead of keys, Mr. Lawson is playing Bach and Handel with such enthusiasm that he rises off the leather bench every few notes. The air in the open tower is wet and heavy with a March fog, and the rich reverberations of each bell seem to hang a few moments before they blend with the other. Although the traffic beneath the 400-foot tower drowns out most of the sound for the few pedestrians who are about this Sunday morning, those watching Lawson from a catwalk outside his room are fully aware of the power of the instrument. They smile and turn around and around in astonishment as they listen to the tintinnabulation around them.
Fifty miles up the Saw Mill River Parkway at the Melrose School in Brewster, N.Y., eight perspiring men and women stand in an oval pulling ropes in a room twice the size of Lawson's. Above the ceiling, out of view but connected to the ropes, eight wheels rotate eight bells in 360-degree arcs. As if to announce a day of celebration, the bells throw cascades of joyous sound over the fields and stone walls of Putnam County.
The people are change ringers, and the ''music'' they play is complex. To a neophyte, the noise tends toward cacophony. To the trained ear, though, the patterns are like the work of a meticulous musician. In precise rhythm each ringer pulls the rope, holds it until his turn, then releases it. The pace is lively, the concentration intense.
Carillons and change ringing are the twin states of the art of bell ringing today. But with only 13 change-ringing towers and 180 carillons in the United States, few Americans have the opportunity to hear these unusual instruments. In most places families come to church to the sound of artificial bells - electronic carillons (metal rods struck by tiny hammers and amplified over loudspeakers) or tubular carillons (large tubes similar to those used in symphony orchestras). Even when real bells are used, they are often chimes - bells rung electronically from a clock or an organ console. True carillons such as Riverside's are played mechanically by means of clavier-operated wires, cables, and springs.
Carillons were developed in Belgium and Holland during the 16th century. They were community musical instruments rather than voices of the church.
Change-ringing bells, on the other hand, became popular in England as communication devices, telling distant farmers of deaths or floods.
The first set of North American change-ringing bells was installed in Old North Church in Boston in 1745. Among the initial ringers to agree to ''attend there once a week on Evenings to Ring the Bells for two hours Each Time'' was young Paul Revere. But the activity never developed ardent followers as it had in England, and many churches, including Old North, eventually converted the change-ringing bells to simple chimes for lack of ringers.
In recent years there has been a revival of interest in change ringing in North America. Nine sets of change-ringing bells have been either refurbished or installed in the past 20 years. The bells at Old North were reactivated Sept. 3 to celebrate the bicentennial of the Treaty of Paris.
Controlling a bell you can't see, while listening to several other bells and watching other ropes, all the while keeping track of where you are in the scheme and making sure you don't get your arm caught and fly headfirst into the ceiling - change ringing is not for the lazy.
''If any one of the ringers has not done his or her homework,'' says Geoffrey Davies, ringing master at the Church of the Advent in Boston, ''then the ringing collapses like a pack of cards, and the result is din.''
It's almost noon as Lawson starts his second concert of the day. First the tinkling of smaller bells just above the room. Then the full carillon bursts into sound with ''The Old 107th,'' an Episcopal hymn. Lawson's loosely clenched fists deftly strike the batons. His feet jump like puppies from pedal to pedal. His jowls shake and his eyes are bright. His lips pulse swiftly in and out. Above and beneath and to every side the bells ring out their song. Lawson is in his glory. With every muscle straining, he seems very close to heaven.