NEW DELHI, JAN. 16 -- L.K. Jha, 74, a noted economist who served India for half a century as civil servant and adviser to prime ministers and who was ambassador to the United States from 1970 to 1973, died today of cardiac arrest in a hospital in the central Indian city of Pune. He had lung and kidney ailments.

He had been Prime Minister Rajiv Gandhi's adviser on administrative reforms since July 1985 and also was a member of the Rajya Sabha, the upper house of Parliament. Mr. Jha had been a secretary to prime ministers Lal Bahadur Shastri and Indira Gandhi and had been governor of the state of Jammu and Kashmir.

He had been India's representative to a number of international bodies. He also had been chairman of the United Nations Group of Eminent Persons on Multinational Corporations in 1974, and an alternate governor of the World Bank from 1960 to 1964.

Mr. Jha epitomized the "steel frame" of Indian government, the members of an elite civil service who serve in a variety of positions during their careers and who are widely credited with keeping this diverse, poor and heavily populated country on a stable political course.

However, it was as a civil servant in a variety of ministries dealing with the country's economy that he built his early reputation, and he is widely credited with having forged India's mixed economy, in which socialist and capitalist principles coexist. He served for three years as governor of the Reserve Bank of India, the country's central bank.

Mr. Jha entered government service in 1936 as a member of the Indian Civil Service, the elite corps that served under British colonial rule. This group is widely credited with keeping the country functioning during the chaotic days of independence and partition of the subcontinent into India and Pakistan in 1947.

Mr. Jha was a native of the eastern state of Bihar. He was educated at Benaras Hindu University and later at Cambridge University's Trinity College, where he studied under the famed economist John Maynard Keynes.

Mr. Jha moved as comfortably with the power brokers of Washington and London as he did with those of New Delhi. Even after he ended formal government service, his views constantly were sought out by leading political figures and similarly were heeded when he felt it necessary to speak out on a major issue.

Prime Minister Gandhi today praised him as "a public servant of rare brilliance, dedication and achievement."

Survivors include his wife and two daughters.

WILLIAM H. SHERIDAN SR.,

78, a retired official of the old Children's Bureau and the Department of Health, Education and Welfare, died of cardiopulmonary arrest Jan. 13 at Holy Cross Hospital.

Mr. Sheridan, a resident of Silver Spring and a former resident of Germantown, was born in Gates Mills, Ohio. He graduated from Hiram College in Hiram, Ohio, and received a master's degree in social service at what is now Case Western Reserve University in Cleveland. He received a law degree at the Cleveland Marshall Law School in Cleveland.

During World War II he served in the Navy in the Pacific.

In 1948, Mr. Sheridan moved to the Washington area and went to work in the Children's Bureau in the Social Security Administration. The bureau was included in HEW when that department was established in 1953. In 1969 its functions were transferred to the Office of Child Development.

Mr. Sheridan was a juvenile court official in Cleveland and his work at the Children's Bureau involved juvenile delinquency programs. He retired in 1974.

Survivors include his wife, Genevieve Sheridan of Silver Spring; three children, William H. Sheridan Jr. of Frederick, Gail Craddock of Silver Spring and Susan Jenkins of Montgomery Village; three sisters, Irene Collins and Anne Sheridan, both of Rocky River, Ohio, and Edith Sheridan of Shaker Heights, Ohio, and five grandchildren.