James Watt’s work on developing the steam engine lead to the discovery of what are now called Watt’s curves and linkages. The animation above shows how they are constructed from linking a fixed radius to another with a rod. I tweaked the lengths here to make a lovely heart. With different lengths it is possible to make sections of the red curve almost exactly straight. Watt was able to use this to double the power of a beam engine, and nowadays this is used in the suspension systems of some cars. [more] [more2] [code]