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"For many purposes compressed air is preferable to steam or other gas for use as a motive power. In such cases air compressors are used to compress air. These are made in many forms, but the most common one is to place a cylinder, called the air cylinder, in front of the crosshead of a steam engine, so that the piston of the air cylinder can be driven by attaching its piston rod to the crosshead in a manner similar to a steam pump." —Hallock 1905

Air Compressor

"For many purposes compressed air is preferable to steam or other gas for use as a motive power. In…