Wilson C. Piper '39, a life Colby trustee and a stalwart supporter of the College for more than 50 years, died January 31 in Hanover, N.H., at 79.     A native of Caribou, Maine, Piper graduated from Colby Phi Beta Kappa, earned a law degree at Harvard and worked for the next 30 years at the Boston law firm of Ropes & Gray where he was a prominent tax attorney.     Piper's broad and deep association with Colby included service on the Alumni Council; the Boston Colby Alumni Association, which he led as president for several years; and the College's Board of Trustees, which he joined in 1959.      President Robert E.L. Strider lauded Piper's commitment to Colby in 1975 when Piper was presented an honorary degree. "It is impossible to single out his most important contributions," Strider said. "To all his labors for his College he has brought wisdom, insight and tolerance for the inscrutable mysteries of academe."     The author of Colby's revised by-laws in 1958, Piper had leadership roles in all of the College's capital campaigns over the past 40 years. He received a Colby Brick Award for outstanding service in 1974 and in 1983 was presented the Ernest C. Marriner Distinguished Service Award. Piper Residence Hall was named for him in 1986.     The Clara Piper Professorship and Research Fund, established in 1990 in memory of his mother, Clara Collins Piper '14, supports scholars in international relations and environmental studies.     Predeceased by his sister, Prudence Piper Marriner '41, he is survived by his wife of 53 years, Mary "Peg" Piper; two daughters, Elizabeth Piper Deschenes '75 and Stephanie Piper; a son, Charles '70; and a nephew, John Marriner '70.