Philo was born on July 6, 1798 in Sherman, Connecticut, United States, the son of Philo and Sarah (Penfield) Stewart, and a descendant of Alexander Stewart who came to New London, Connecticut, from Ireland about 1719. At the age of ten, because of his father's death, Philo was sent to live with his grandfather Penfield in Pittsford, Vermont, and when fourteen years old was apprenticed to an uncle in Pawlet, Vermont, to learn harness making, serving for seven years.
He early showed much mechanical aptitude and attended the Pawlet Academy for three months each year.
Stewart made the journey of nearly 2, 000 miles on horseback, carrying his entire outfit in a pair of saddle-bags, preaching along the way, and completing the journey at an expense to the Board of ten dollars. At the mission he superintended its manual labor, taught the boys' school, and conducted services on Sunday in various Indian settlements.
Ill health took him back to Vermont in 1825, but he returned in 1827, bringing several new workers.
His wife's impaired health necessitated their leaving the mission in 1830 and Stewart in 1832 joined his fellow student of Pawlet Academy days, John J. Shipherd, then pastor of a church in Elyria, Ohio. Both were ardently religious and born reformers. Together they evolved the plan of a community and school where their ideas could be realized. Stewart was especially attracted by the thought of a school combining study and labor with such economy that students might defray all their expenses.
The result of their efforts was the founding of Oberlin. Together they selected a tract of forest land, about nine miles from Elyria, on which Oberlin now stands. During Shipherd's absence of several months in New England to acquire title to this land and seek funds and colonists, the Stewarts were with the Shipherd family in Elyria. Stewart occupied himself in perfecting a cookstove, undertaken originally to meet a need in Mrs. Shipherd's kitchen, the manufacture of which he hoped might yield substantial income to the projected school.
At the same time he had general supervision of the work at Oberlin, meeting and encouraging the colonists as they came from the East. When the school was opened in 1833, the Stewarts took charge of the boarding hall. They had pledged themselves to the service of the "Institute" for five years, with no compensation beside their living expenses.
For the first year Stewart was also treasurer and the general manager; but, disagreeing with his associates in his opposition to radical abolitionism and to the admission of negro students, he resigned in 1836 and returned to the East.
He now tried to perfect a planing mill which had been projected at Elyria, but the financial crash of 1837 ruined the undertaking and he came into financial straits. Making his home in Troy, he returned to the stove project, which proved so successful that in thirty years more than 90, 000 stoves were sold.
The patent for the "Oberlin stove, " granted June 19, 1834, he had deeded to the Oberlin Collegiate Institute. Other patents were issued to him on September 12, 1838, April 12, 1859, and April 28, 1863.
He died in 1868.
Being attracted to Christian service, in 1821 he accepted appointment by the American Board of Commissioners for Foreign Missions as an assistant missionary among the Choctaws at Mayhew, Mississippi.
In 1828 he married Eliza Capen from Pittsford, Vermont.
