[–] gene-h 9y ago ↗ A kids book from 1972 proposed something similar, deliver packages by weighting them for neutral buoyancy and pumping them down pipelines[0].[0]http://2010book.tumblr.com/post/324091567/the-restaurant-kit...
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[ 3.1 ms ] story [ 5.7 ms ] thread[0]http://2010book.tumblr.com/post/324091567/the-restaurant-kit...