Looking for death certificate and cause of death of Harmon John Smith.

Born in Walcottsville, NY 1-29-1866.  Died in Niagara County, NY.  Was a twin.  Family says he died while working for NY Central RR.  Would like to confirm.  Cannot find death certificat

Have checked Niagara County NY records without success.

any way to find info through NY Central RR records?  Do any exist?

he is buried in Wolcottville.