Here's the information that I have on the James Desper who might be your g-g-grandfather:
1.James Walter Disper was born on August 2, 1850 in Medway, MA to Joseph and Julia Ann (Niles) Disper;
2.James Walter Desper married Harriet R. Higgins on March 12, 1873 in Milford, MA;
3.James and Harriet had several children over the next few years in Medway, Holliston and Franklin, MA; and
4.James W. Desper died on June 14, 1892 in Franklin, MA.
I have a great deal of information on various branches of the Desper family.In case I have the wrong candidate above, what was the name and birth place and date, etc.of your g-grandfather?I may recognize him.
I hope this helps.In any case, good luck in your search.