Freeman Dart

Freeman Dart, born about 1839 in N.Y., is my husband's great grandfather.I found him in the 1870 Grand Rapids, Michigan census.He was married to Sarah Porter who was born about 1849 in Ohio.They had several children: Calvin, Lena, Fay, Bert, and I think Eria.Am looking for anyone that is related or has any info on them.
Mary Dart