He was born in Walpole, New Hampshire, the son of William Hooper and Elvira Pulsifer Hopper, and grew up on his parents' farm.

[3] After three years as head of the high school in Keene, New Hampshire, from 1877-1880, he was appointed professor of chemistry and geology at Adelphi College, Brooklyn, where he taught until 1889.

[4] In 1889 he was appointed as General Director of the revitalised Brooklyn Institute of Arts and Sciences (BIAS), where he had been a Fellow, and (continuing the earlier example set by Agassiz) was instrumental in the founding of its summer school Biological Laboratory (Bio Lab) at Cold Spring Harbor, Long Island, in 1890.

[2] Hooper greatly expanded the institute's work of presenting a wide range of public lectures and concerts, quadrupling its membership.

The Brooklyn Museum will embrace all known human history, the infinite capacity of man to act, to think, and to love, and the many departments of science and of art which he has developed.

He was instrumental in setting up the Old Rockingham Meeting House Association in 1911, for the continued preservation of the newly restored Vermont church which his great-great grandfather David Pulsipher had helped to found in 1778.