The Barnum Family, 1517-1904 says that he had a son.
From Binghamton: its settlement, growth and development and the factors in its history 1800-1900 page 963: Silas G. Barnum was born in the town of Union (Broome County, NY), May 21, 1846. He was a son of Lucas Barnum, who was a native of Schoharie County. His mother was Lucas Barnum's second wife: her maiden name was Maria H. McCollum. He has a brother, William H., and a sister Lydia A., also a half brother Enoch, and two half sisters, Melissa and Lucy M. He was educated in the common schools. On September 6, 1862, he enlisted in Co. E, 50th NY Vol. Engineers, and was discharged at Fort Barry, Va., June 13, 1865. He was married September 4, 1867, to Jane, daughter of Samuel Gallup. They had two daughters; one died in infancy, the other, Leolie M. died November 18, 1884, aged sixteen years. He was a farmer until 1884, when he engaged in the mercantile business with G. W. Bixby at North Sanford, and in 1888 bought his partner's interest. In 1894, he sold the business and purchased of Mrs. M. L. Kniskern the insurance business of J. W. Kniskern, deceased, which business he is still conducting. In 1875, he was elected superintendent of the M.E. Sunday School and is now serving his twenty-fifth year as superintendent. In February 1899, he was elected town clerk which office he now holds.
According to Veterans administration records, he was an Artificer with Company "E", 50th New York Engineers and received a pension as an Army Invalid.
Sometime following the death of his wife, Silas G. Barnum moved to Saint Petersburg, Pinellas County, Florida where he appears in the 1920 Census.
According to the Florida Death Index, Silas Gould Barnum died in 1936 in Pinellas County, Florida.