"… Mrs. Martha (Spencer) (Cone) Brainerd d. May 3, 1796, ae. 50 yrs. … buried in Moodus Cemetery, Moodus, Conn."
"The late D. W. Patterson said Joshua m. (3) Martha (Spencer) Cone, but Mr. W. W. Cone, author of the Cone Genealogy, stated that Joseph Cone's grandchildren said that she was never married [remarried?]. The Millington church records note her death as widow Cone (distracted). I [Lucy Abigail Brainard] leave it for others to solve, and find the facts."
The identification of Joshua Brainerd's third wife as the daughter of Joseph & Martha (Brainerd) Spencer appears to be inaccurate. Joseph Cone is said to have died in 1779, and his youngest known child with this Martha Spencer was born in 1777. On the other hand, Brainerd married his Cone widow in 1773, so she must have been a different widow Martha Cone.