Three pioneers of engineering science have been immortalized through the use of their names as units in the SI system, representing energy, temperature and power. They are James Joule, James Watt, and William Thomson (Lord Kelvin) and it is likely every practicing refrigeration engineer, designer, technician and mechanic uses at least one of their names every day of their working lives. They create an interesting weave in space-time. This column talks about James Joule's radical notion that mechanical work could be converted to heat.