Samuel Dickinson Hillman was born to Samuel and Susan Dickinson Hillman of Blackwood, New Jersey, on January 18, 1825. Not much is known of his life before he entered the Dickinson College Grammar School in Carlisle, Pennsylvania in 1845. A member of the Belles Lettres Literary Society, Hillman graduated from the College in 1850, and received his master's degree two years later. While working towards this degree, he taught in West Chester, Pennsylvania from 1850 to 1851. Hillman was then appointed principal of the Grammar School, an office he would occupy for nine years.
In 1860, Hillman was selected by the College to serve as professor of mathematics and astronomy. Two years later he became the treasurer for the Board of Trustees, and he would remain so until 1868. By April 1868, Hillman was residing in West College as the senior faculty member; however, President Herman Merrills Johnson died suddenly at that time, and Hillman was selected to serve as president pro tempore due to his seniority.
Like William Henry Allen before him, Hillman was a temporary replacement not to be considered a candidate for the presidency. When a special trustee meeting of September 8, 1868 selected Robert L. Dashiell as president, Hillman returned to his position as professor. He would remain with the College for another six years.
In 1874 Hillman was removed from the faculty by a Board of Trustees' vote that vacated the positions of all the professorships in order to rejuvenate the faculty. He and fellow professors William Trickett and John Stayman were defeated in a vote to regain their positions. Hillman accepted a quarter of his yearly wages ($300) as a concession. Lawsuits ensued, and the matter was settled when the Board offered to pay a full year's salary to each of the three deposed professors. Hillman was paid the additional year's salary in addition to the $300, and he and his family were allowed to remain in West College until April 1875.
Following his removal from Dickinson, Hillman accepted a professorship at the newly-established Cumberland State Normal School at Shippensburg, teaching natural science from 1874 to 1880. During this time he was awarded a Ph.D. from Lafayette College in 1878. Hillman's next appointment was as principal of a high school in Rahway, New Jersey in 1882. This position was followed by three professorships: mathematics at Newton Academy in New Jersey, 1883-1889; mental and moral philosophy at Taylor University, 1890; and Greek and Latin at a military academy in New York, 1892. After nearly half a century of educational service, Hillman retired from public instruction in 1898.
Hillman married Cornelia Gaylord Wing of Sodus, New York on July 24, 1855. The couple had three children: Conway Wing, Willis Gaylord, and Amy Dickinson Hillman. The eldest, Conway, was a member of the Dickinson College class of 1873. After fourteen years of retirement, Samuel Dickinson Hillman died at his home in Newark, New Jersey in December 1912.