Robert, I looked in the TAM FAMILY book by Fred Tam and Joseph H. Tam is not in there.There is a Joseph Stephen Tam, but they are not the same person.I tried Ancestry.com foryou and only found Joseph Tam as the son of Milton Tam and Urbana Ohler.I don't believe this is the right Joseph either because I think he was born about 1866.
The next place I checked was in the LDS site, familysearch.org.They had an IGI on your Joseph H. Tam.Here is the information I found on him there....Joseph Hamilton Tam born April 8, 1858 Woodbridge, San Joaquin, California son of Joseph Harrison Tam and Sarah Glassford.Joseph Harrison Tam married Sarah Glassford on September 12, 1846 in Lafayette, Tippecanoe, Indiana.That also from IGI.They also have in the IGI that Joseph Harrison Tam was born Nov. 19,1812 PA to James Hamilton Tam and "Mrs. Tam".
In the 1920 census, your Joseph H. Tam can be found in CA, O'Neal Twp, San Joaquin Co. ED 152 pg 30B image 700.
I wonder if your line of Joseph's come from the Joseph Tam in Martha Downey's will??I don't know anything about that line, but it looks like they sure stuck with the name Joseph.Here's a copy of Martha Downey's will if you don't have it already... Sussex County, Delaware Probate Records, 1680-1800 Prim Name: Martha Downey Admin Name: Will Made Date: 28 Oct 1771 Will Loc: Heirs Name: mother Mary Turner; cousins Benjamin Lear, John Tam, Joseph Tam, Martha Stevenson, Rhody Stevenson, Isaac Templain, Mary Templain and Richard Templain; father-in-law Samuel Turner; aunt Sarah Tam Exec/Trus Name: aunt Sarah Tam and cousin Benjamin Lear Wit Name: Samuel Hand, Mary Vent, Thomas Hall Will Probate Date: 02 Dec 1771 Will Book: Arch. vol. A69; Reg. of Wills, Liber B Page: 170; folios 433-435
You could check on this older Joseph Tam maybe through this military record...Joseph Tam, DE Militia, Co. 8 Rgt., 1814-1815 private/private
This may also be your Joseph H. Tam...CA State Roster, 1909, Gov't and Military Rcds...Jos. H. Tam, notary, pg. 230, residence: Bakersfield county: Kern
Well, maybe this will have some information in it that you didn't previously have.I wish I knew where your Joseph line connected in with either the John Tam line of VA 1796 or our James Tam line that came to DE, but I don't.
Keep us here at the Tam forum in mind if you make a connection, and we'll keep an eye out for you too.