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"To avoid friction and heat, the piston is not in contact with the cylinder in which it works."

Deleuil's Air-pump

"To avoid friction and heat, the piston is not in contact with the cylinder in which it works."

"To avoid friction and heat, the piston is not in contact with the cylinder in which it works."

Piston and Barrel of Deleuil's Air-pump

"To avoid friction and heat, the piston is not in contact with the cylinder in which it works."