Zachos continued living in Boston for another two years. He became a Unitarian Minister. He gave twelve lectures at the
Lowell Institute. Both Samuel Gridley Howe and Zachos departed Boston at around the same time. Samuel Gridley Howe traveled back to Greece to carry relief to the Cretan refugees and Zachos moved to
Meadville Lombard Theological School. In May 1866, he became the Professor of Sacred Rhetoric. While at the Theological School, he established another Literary Society. American author, historian, and Unitarian minister
Edward Everett Hale spoke very highly of John C. Zachos. Historian
Earl Morse Wilbur describes Zachos's call to minister at the
Independent Congregational Church (Unitarian) of Meadville (Pennsylvania), writing: "A call was given, January 28, 1866, to the Rev. John Celivergos Zachos of West Newton, Mass. He accepted the call and began his ministry here at the beginning of May, at a salary of $1500, in addition to the rents of the minister's house, and with four weeks' annual vacation." Wilbur wrote further:Something of the schoolmaster was apparent in his style of preaching. He was a versatile man, with an uncommonly wide range of interests; a Greek in temperament as well as by birth, fond of abstract themes, and inclined to consider subjects rather from the philosophical or speculative than from the practical side. Yet, though fluent in language, he was not considered an especially strong preacher, nor yet a superior pastor. In addition to the work of his ministry, he was professor of Sacred Rhetoric and Oratory in the
Theological School during the two years of his residence here and continued to hold this office during the year after his departure, returning to give lectures. To him, it is said, is due the suggestion that led to the forming of the Meadville Literary Union in December 1866. Mr. Zachos resigned in July 1868 and left Meadville at the beginning of October in order to accept a call to the church at Ithaca, N.Y. His departure was generally lamented, as the loss of a faithful minister who was ready to devote himself to every good cause, and who had endeared himself to all classes by his affable manner and his kindness of heart. By 1868 Zachos moved to Ithaca, New York to the Ithaca Chapter of the Theological Seminary. He remained associated with the former institution until 1871. While at Ithaca Zachos also lectured and taught classes at the newly founded
Cornell University. In 1871, now 51 he moved to New York City where he would stay until the time of his death.
Peter Cooper and John C. Zachos became good friends. Zachos influenced the foundation of
Cooper Union. He taught literature and public speech. In 1876, he was Peter Cooper's first biographer. He was a Professor and Library Curator at Cooper Union. Zachos invented a medical device called an Improvement to Abdominal & Spinal Supporters. A patent was filed on July 16, 1872. The No. was 129202. The device was also patented in England. Due to his legendary reputation in the Civil War as an Army Surgeon. Zachos also became medical advisor to the Butler Health Lift. He collaborated with David Butler the inventor of exercise equipment. Together, they wrote instructional books on health and exercise and the benefits of using the equipment. On December 24, 1875, he filed patent number 175892 for typewriters and phenotypic notation applications. The machine was a stenotype used for printing legible English text at a high speed. He obtained 10,000 dollars in investment capital for his invention. He continued his advancement of oratory for the next two decades. He was a proponent of the Delsarte System of Oratory founded by
François Delsarte. He also advocated the James Rush classic,
The Philosophy of the Human Voice. James Rush was the son of
Benjamin Rush. Zachos's lectures were very popular at Cooper Union. Namely, on Tuesdays and Saturdays, the crowd would exceed 100 to 200 people.
Peter Cooper told
William Cullen Bryant to personally observe Professor Zachos's lecture. In "The Letters of William Cullen Bryant" Bryant called Zachos an oratory genius. Due to his poetry lectures he also gained the recognition of
Ralph Waldo Emerson and
James Russell Lowell. His writing was not confined to literature. Zachos also wrote about philosophy, mathematics, science, metaphysics, and other scientific branches. Under the pseudonym "
Cadmus" Dr. Zachos wrote about financial and economic subjects that were published in various New York City publications. On January 7, 1896, Harriet Tompkins Zachos died. Roughly two years later on March 20, 1898, John Celivergos Zachos died. His funeral was held at the
Church of the Messiah (Manhattan). Among the many in attendance were his
pallbearers S. Packard,
Augustus D. Juilliard Former NYC mayor
William Lafayette Strong and Union army brevet brigadier general
Henry Lawrence Burnett. At the time of his death, his residence was 113 West 84th Street New York City. ==Zachos Method==