How was a unit of energy first defined?

[Alutoe]

How was a unit of energy first defined? I know we measure energy in units of Joules as named after James Prescott Joule and a Joule is defined as 1kg*(m/s)^2 But I can't find any information on the history of the unit itself, how and when was it first defined, by whom? How was it decided or discovered that energy is measured in units of 1kg*(m/s)^2 ?

 

[voko]

See this article. http://en.wikipedia.org/wiki/Vis_viva The unit [mass] x ([length]/[time]) ^2 was natural given the definition.

As for the unit "Joule", I think it was introduced with the SI system. http://www.bipm.org/en/CGPM/db/11/12/