In 1698, Sherpali's steam engine was patented. The characteristic of this steam engine is that it has no steam cylinder and no piston. Its advantage over Barbain's machine is that it has two boilers.
The boilers are one big and one small. Only add 2/3 of the water to the big one. After heating and boiling, when the water vapor is full, move the handle and guide it to another air chamber. , then plug the stopcock, and then add cold water to the air chamber. The water vapor inside will immediately condense to form a vacuum, so that the groundwater under the air cylinder can be naturally pumped up.