PROVIDENCE, R.I. (AP) — Former Brown University President Donald F. Hornig, who worked on the atomic bomb and was a scientific adviser to three U.S. presidents, has died. He was 92.

His son says Hornig died Monday. He had Alzheimer's disease.

Hornig was the Ivy League university's president from 1970 to 1976. He also taught at Princeton and Harvard.

Hornig was a Harvard-trained physical chemist and one of the youngest group leaders on the Manhattan Project that developed the atomic bomb during World War II. He designed the firing unit that triggered the simultaneous implosion of the bomb's plutonium device.

Hornig advised presidents Eisenhower, Kennedy and Johnson, then became president at Brown, where he restored the university to financial health.

He then joined Harvard's School of Public Health. Harvard honored him last year for being a "visionary scientist and educator."