What did James Watt do to the steam engine?

In 1765, an engineer named James Watt was asked to repair a model of a Newcomen engine. While fixing it, he saw ways to improve it. He added a box called a condenser that helped keep the piston cylinder hotter. Watt also figured out how to have the steam push the piston in both directions, making a faster engine. Watt's improvements made the steam engine much more efficient. Watt also came up with the idea of comparing the power of his steam engines to the amount of work a horse could do.