Justin Rolph Loomis was born on August 21, 1810, in Bennington, New York. He attended the Hamilton Literary and Theological Institution at Hamilton, New York, but graduated from Brown University in 1835. In 1836, he joined the faculty of Waterville College in Maine, beginning as a tutor and serving as Professor of Chemistry from 1837 to 1852. He was ordained a Baptist minister in 1845. In 1854, he assumed the position of Professor of Natural Science at the University at Lewisburg, and in the same year he was awarded an honorary Ph.D. by the University at Lewisburg.

Professor Loomis became President of the University at Lewisburg in the fall of 1858 and he served in this capacity as well as that of professor for twenty-one years. During his tenure as president, the University experienced grave financial difficulties, which were caused by the debt incurred before the Civil War, as well as by a declining enrollment. In 1863, the Board of Trustees approved the sale of scholarships which would allow the purchaser to send a person to the University for a specified number of years. For instance, a perpetual scholarship could be purchased for the sum of $500.00, which would guarantee that one person could attend the University in perpetuity without paying tuition. The Trustees abandoned the sale of scholarships in 1865.

Justin Loomis resigned as President in 1878 after a bitter dispute concerning the dismissal of Charles S. James, Professor of Mathematics, which provoked demands for the president's resignation by the Alumni Association. He died in Lewisburg on June 22, 1898, and he is buried in the Lewisburg Cemetery.