E. Power Biggs, 70, the organist who was famed as an interpreter of Bach and for his long-running weekly radio recital series, died Thursday in a Boston hospital after surgery for bleeding ulcers.

Although Mr. Bigg's concert work had been curtailed in recent years because of arthritis, he had toured widely in the United States and Canada in the past, and visited Europe to make recordings on the historic organs of old churches and cathedrals.

He was probably best known, however, for his weekly recitals on the CBS radio network, which began in 1942 and continued for 16 years.

Heard by millions, these recitals, performed on Mr. Biggs' favorite instrument, the baroque organ in the Germanic Museum at Harvard University, helped make the British-born organist a celbrated figure in the worlds of music and entertainment.

With the baroque organ, a modern instrument designed to approximate as closely as possible the sound of the great organs of the 18th century, Mr. Biggs during 1945-46 made the first broadcast presentation of the entire organ works of Bach.

Credited by a leading critic with having "created a kind of music renaissance of . . . the organ," Mr. Biggs also included in his radio recitals all the organ works of Handel, Mozart, Mendelssohn and Brahms, as well as new works specially commissioned from leading contemporary composers.

Despite his devotion to an instrument of enormous power and majesty, Mr. Biggs had a style of play more restrained than extravagant, and was himself known as a man of cheerful informality.

Organists, he once said, "are often considerad to be on the lunatic fringe of musicians, probably because they hang around churches all the time."

A teacher and scholar who had been a church music director as well as concert performer, he said he advised his pupils to "mix with other sorts of musicians, never with organists."

Mr. Biggs, who was born Edward George Power-Biggs, on March 29, 1906, in Westcliff, Endland, was educated at Hurstpierpoint College in Sussex and decided on a career in music after two years of study in electrical engineering.

Of his belated start, he expressed little regret."It is practically impossible to be an infant prodigy on the organ," he noted. "Pedals are so low a tot can't reach 'em."

The effect of his electrical engineering training is not clear. However, it is known that Mr. Biggs deplored the increasing use of electronic organs in churches and concert halls. Of one installed in Carnegie Hall, he said it "cheapens the hall and ruins its image as a place of excellence."

A 1929 graduate of Britain's Royal Academy of Music, Mr. Biggs came to the United States in 1930, made his New York debut in 1932, and became a naturalized citizen years later. He lived in Cambridge, Mass.

In his style of play, his fondness for the sound of the baroque organ and in his efforts to seek out for recording purposes the organs used by the classical figures of the past, Mr. Biggs appeared to be following his belief that "authenticity is best in both organ and performance."

He is survived by his wife, Margaret.