Britain.

No single person was responsible for the invention of the steamboat. Rather, it was a long series of innovations and improvements, starting with the first steam engines of Thomas Savery and Thomas Newcomen in the early 1700s. Early steam engines were "atmospheric," which meant that heated water created steam that raised a piston in a cylinder; when cold water was injected into the cylinder, the steam condensed and atmospheric pressure drove the piston down, creating the power stroke. The Newcomen engine was called the "miner's friend," because it was typically used to pump water out of British coal mines. By 1725 the steam engine was also used for raising water to turn a waterwheel which then drove machinery. The next significant innovation was James Watt's invention of the separate condenser and the "double-acting" engine, both of which greatly improved the efficiency of the steam engine. With their...