That's a huge pneumatic hammer used to set big iron pylon into the Chicago river. You can alternately hear the beating iron and the pneumatic puffing as a original mechanical industrial rhythm!
Recorded with binaural soundman mikes.

Comments

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  BirthNight 3 years, 4 months ago

  This is one of the best field recordings I've ever heard! Great find!
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  daveincamas 4 years, 5 months ago

  This is really fun if you start several them slightly offset in time. Thanks for posting this!