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.
The railway steam locomotive is a steam engine on wheels, the very earliest ones are just a large boiler driving pistons in exactly the same way as stationery engines in factories.