- In Turin in 1909, Luigi Giarlotto developed the first espresso machine that included a water pump.
- Machine designs by Guido Snider and Marius Malausséna featured heat exchange and multi boiler capabilities, running on both gas and electricity.
- Tests by Barista Hustle suggest that machines as early as the 1920s would have been able to produce persistent, long lasting crema.
- Electric pumps were not employed on a machine until much later. Beniamino described the first known electric pump used on a coffee maker in his patent from 1950 for a machine called the Cordor.
- In his 1910 patent, Pier Teresio Arduino described a batch-brewing group head to a large-scale upright boiler design with the first known screw piston for pressing the water out of the group head.
- The screw piston concept lay dormant for three decades. It resurfaced in 1936 in a patent drawn up by Antonio Cremonese.
- Cremonese’s widow, Rosetta Scorza, inherited his patents and sold the screw piston patent to Giovanni Achille Gaggia, who paid her 1,000 lira (valued at around 1,000 euros in 2021)
- Gaggia added a spring to the cremonese concept and patented his lever group head in 1947.
- Gaggia’s elegant spring lever design produced a pressure profile that involved an extended preinfusion period then very high pressure as high as 11 bars of pressure. This pressure profile gradually declined as the show advanced down to around 4 bars at the end of a shot.
Thermosyphon The mechanism that controls the brewing temperature in most single-boiler machines. Water is superheated in the heat exchanger and loses heat as it passes to the group. Cooler water then passes back to the heat exchanger by convection.