The big problem with atmospheric railways was sealing the slot in the tube where the piston inside the tube connects to the load. Early atmospheric railways use

The big problem with atmospheric railways was sealing the slot in the tube where the piston inside the tube connects to the load. Early atmospheric railways used oiled leather, beeswax, and tallow. Those were not really good enough materials for the job. There are solutions for this today. They're widely used in rodless pneumatic cylinders.[1] The seal is flexible metal strip to metal, forced closed by the interior pressure of the cylinder. In the 1980s, there was a brief revival of the technology by Aeromovel, which built a few theme park and airport systems. None seem to be still running. [1] https://tameson.com/pages/rodless-cylinder https://tameson.com/pages/rodless-cylinder