I am also descended from John Buckman of Boston. The geographic lineage of my branch goes from Boston to Ipswich to Worcester, MA to Bethel, VT to Potsdam, NY to Sangamon Co., IL in 1834. A large fraction of the family has remained in and around Sangamon County ever since. I just published everything I have on my website at Genealogy.com and would welcome any additions or corrections. See "The Buckman Family of Sangamon County, Illinois."