What is the furthest back anyone has traced their family tree?

[jamesy boy]

Obviously, the Royals can trace theirs back centuries, but what about non-aristocratic people?

Just curious.

[tubeway]

On my mums mums mums side I can get to 1385 - best on other branches - my mum in laws mum to 1599. On the rest it is about 1800-1840 - I have both fairground travellers and polish imigrants in my blood (lets face it I'm a mongrel) which make some branches difficult to trace

[Peter Pedant]

This is to CCorday - is this Charlotte Corday, the one who knifed Marat, or that leggy good-looker on ER?

Anyway my Queen, your forebear is quite famous, and i just thought I would fill in a bit. Benjamin Thompson was indeedy a famous scientist. He showed that work and heat were both a form (of what we call energy) . 1794. You know when you drill a hole in a metal bob? well if you do this big time, you end up boring a hole in a cannon,lengthways. Rumford added a bit of water and after 24 hrs showed that there was a rise in temp of 1/2 deg Fahrenheit (I think). So not only did he show that the two forms of energy were interchagneable,he could also give an estimate (first ever) of the constant. In foot-pound-second units of course. I think it is 4.35 cals/joule in CGS. 

He must have been an Irish Roman Catholic and anyway was a Count of the Holy Roman Empire. Not an Earl. I had a bit of a double take when i first read your posting, because you dont seem to realise his importance. Rumford is famous like Einstein.