"RI Vital Records: New Series" Vol. 6, p. 66, gives his date of birth as 6 Aug 1822. However, the RI Cemetery Database has his mother's year of death as 1820, so one of them must be wrong. He is age 30 in the 1850 Federal Census, so I am using 1820 as the year of birth. In 1850 the family is living at East Greenwich with Cynthia's mother, Lydia Sprague.
John Remington Congdon is mentioned in the will of his grandfather, Henry Remington.