Platt Barnum and his wife Alethea Barnum were second cousins. The Barnum Family, 1517-1904 states that they had four daughters and three sons. According to a deed, Platt purchased land in Thompson, Sullivan County, New York in 1821. Fallsburgh (now called Fallsburg) was established as a town in 1826, with the portion containing Platt's property apparently taken from the Town of Thompson.
The source for the children of Platt and Alethea Barnum was the Neal Family Bible, where Barnum entries were made. It shows Barnum for the surname of the first child, then ditto marks under Barnum through Abel; Lewis Henry Barnum was entered as L. H. B.; Amanda was entered as Amanda B.; finally appears Albert S. B.
Descendant Diane Rousseau typed the information from the Bible for Mrs. Sally Cole, and typed it as written, in a letter dated August 31, 1980. However, in 1995 she typed all of the genealogy contents of the Bible, had it notarized and it was published in the Connecticut Society of Genealogists Inc. "Nutmegger", September 1995 issue, Volume 28, Number 2, Pg 242-246. At that time it was clear that the "B" after several given names is for Barnum, not an initial.
From Quinlan's History of Sullivan County, page 262: William Blanchard had the James O'Neill place, which he sold in 1803 to Goold Lord. John Lord bought a place which Isaac Rundle claimed. The Lords were brothers, and after buying the squatter-rights of the occupants, were obliged to obtain the fee simple of a widow Bleecker of Albany, who was the real owner. John and Goold soon left. The place of the latter was owned for many years by Platt Barnum and his heirs.
According to the Genealogical & Family History of Southern New York, Platt Barnum, son of Matthew and Rhoda (Star) Barnum, was born February 19, 1790, died April 23, 1831, in Thompson, Sullivan County, New York. He settled about 1810 and lived there until his death, engaged in farming. His farm was in the Neversink Valley and is known as the O'Neil farm. At their request, his body and that of his wife were buried on their own land, adjoining the cemetery. Platt married Althea, died August 27, 1863, daughter of Abel Barnum, whose line of descent Comes down from Thomas through his son Francis, who married Deborah Hoyt, and had six sons, and one daughter. His sixth son, Abel, was born 1703, achieved distinction as a captain in the War of the Revolution. He was the father of Abel, Jr., whose children were Ira, Daniel Turner, Henry and Althea (wife of Platt Barnum). Mr. and Mrs. Barnum had three sons and five daughters.