I have been following this particular line of Algers from Rhode Island to Connecticut to Vermont to New York to Iowa then to Minnesota. Several siblings from the older Alger line married into the Knight family of New York and Iowa.
Truman Alger was enumerated with a presumed son named Serrel in Cattaraugus County, NY, born about the same time as a son named Serrel to Lyman and Dorcas (Hawkins) Alger in Clinton County, Iowa. I made the incorrect assumption that the Serrel Alger of Union Township, Carroll County, Iowa in 1880 was the son of Truman and Charlott Alger!
A biographical sketch of Lyman Alger of Clinton County, Iowa mentions sons Serrel Alger and Damon O. Alger (both deceased), and daughters Mary J. Knight (living), Almira Berroud (living), and Maria Curtis (deceased). I believe the book "History of Clinton County, Iowa" was published around 1880.
Lyman Alger had (3) marriages. The first one was to Dorcas Hawkins in 1822. Secondly, Martha Knight, daughter of Noel and Martha (White) Knight of Madison County, NY in 1840. Martha Knight was the widow of Serrel Alger (Lyman's brother). Third, to Esther Hawkins, sister of first wife Dorcas Hawkins in 1841. Lyman Alger had (5) children by Dorcas and (1) child by Martha.
Esther Hawkins was murdered on Sept. 25, 1872 and her murder remains unsolved.
Lyman Alger was born September 12, 1800 in Madison County, New York. He was the son of Sarel (Serill, Saral - spellings vary) (born 1766) and Polly (Jackson) Alger. Polly Jackson was the daughter of Joseph and Margaret (Campbell) Jackson. Sarel Alger's parents are unknown, but he did have a brother named Oliver Alger.
Lyman Alger is listed with siblings in the Sarel Alger family Bible. I have a copy of the page.
Coykendall is a familiar surname and occurred along with Alger in Clinton County, Iowa.
Regarding Joseph Serill Alger, brother of Alvah Lee Alger, I do have to question his birthdate of 10-10-1847. This puts him 27 years older than brother Alvah and also makes his father, Serrel (born 1837-38) at 9 or 10 years old when Joseph was born!
I think I have it all straight now. Please let me know if any discrepencies in my info exist or if there is more to fill in.