Thomas Somerville III, 85, the founder and president of Macon Inc., a ceramic tile company, who also was active in service organizations, died Jan. 10 at the Carriage Hill Nursing Home in Bethesda. He had pneumonia and had suffered a stroke.

Mr. Somerville, who lived in Potomac, was born in Washington. He graduated from the old Business High School and George Washington University.

As a young man he joined the Thomas Somerville Plumbing and Heating Co., a family firm of which he became a vice president and director. In 1932, he founded the Washington Brick Co. He retired from both businesses about 1965 and founded Macon Inc., which he ran until his death.

Mr. Somerville was a director and president of the old First Federal Savings and Loan Association. It is now part of Columbia First Federal Savings and Loan, of which Mr. Somerville was a director. He also was a director of the Southern States Industrial Council.

He was a past president of both the Northeast Washington Kiwanis Club and the Kenwood Citizens Association in Bethesda. He was a director of the Bethesda-Chevy Chase Chamber of Commerce and the Washington Board of Trade and a member of the advisory boards of the Boy Scouts and the Montgomery County Boys Club.

He was a member of Mount Pleasant Masonic Lodge No. 33, the Almas Temple of the Shrine, the Kenwood Golf and Columbia country clubs, the Woodmont Rod and Gun Club, and the Sixth Presbyterian Church.

Survivors include his wife, the former Betty Bradford, whom he married in 1929, of Potomac; four daughters, Dorothy Jane Atherton of Potomac, Jacqueline Chadduck of Round Hill, Va., Margaret Beringer of Winchester, Va., and Patricia Donath of Wheaton, Ill.; one sister, Ann Harding of Easton, Md., and 12 grandchildren.