1 teaspoon vanilla extract. 1 large egg. Lightly grease a doughnut (or muffin) tin and preheat the oven to 350F. Sift the flour, cocoa powder, baking powder and baking soda, and then whisk in the sugar, nutmeg and salt.
steam engine. An engine in which the energy of hot steam is converted into mechanical power, especially an engine in which the force of expanding steam is used to drive one or more pistons. The source of the steam is typically external to the part of the machine that converts the steam energy into mechanical energy.
A steam engine is a machine that burns coal to release the heat energy it containsâso it's an example of what we call a heat engine. It's a bit like a giant kettle sitting on top of a coal fire. The heat from the fire boils the water in the kettle and turns it into steam.hoto: Close-up of the piston and cylinder in a steam engine. Our diagram up above shows a very simple, one-cylinder steam engine powering a steam locomotive down a track. This is called a rotary steam engine, because the piston's job is to make a wheel rotate.