Count Benjamin Thompson Rumford (1753–1814), an American-British scientist who made fundamental contributions to the modern theory of heat, which he published in An Experimental Inquiry Concerning the Source of the Heat which is Excited by Friction (1798). He argued that heat is not a liquid form of matter but a form of mechanical energy produced by the motion of particles. When Rumford drilled out cannons, he observed that the cannon remained hot as long as the friction of boring continued. He reasoned that the amount of heat released would be sufficient to completely melt the cannon if it could be returned to the metal. Since more heat was being released than could have been originally contained in the metal, these observations were contrary to the prevailing caloric theory. Rumford calculated a value of the mechanical equivalent of heat, although it was not nearly as accurate as that reported later by Joule. Rumford’s inventions included improvements for chimneys and fireplaces, thermal underwear, the double boiler, a kitchen range, and a drip coffeepot. He also helped disseminate James Watt's steam engine.