The resulting coffee has a layer of foam or crema . 1961 Faema launches a pump based machine. Instead of a hand operated piston the water is forced through the coffee by an electric pump. Water is taken from the fresh water supply and travels through a tube that is passed through the boiler and then through the coffee. Almost all modern restaurant machines are essentially this design.
Modern innovations continue in the design of espresso machines.
Many of these innovations are designed to produce a consistent product irrespective of the operator. Some changes are simple, such as precise metering of the amount of water passed through the coffee. Earlier designs were based on the operator deciding when to stop the flow. This is a fascinating book of photos of coffee machines from 1800 to 1960 with a little bit of history thrown in. The English version is published by Chronicle Books of San Francisco.