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Results for: 'iron%20age'

42:34

HST67/ENVS167#2-3_Private Property and War

By: anbuchan

Third lecture on consequences of Neolithic Revolution and rising agricultural producivity

1:50

Vacuum and Sap Minerals

By: uvmext

A modern maple operation relies on a tubing system with vacuum to maximize sap production. The innovation of plastic tubing originally came as a labor-saving device and not to increase sap yield from individual trees. As the materials used to prod...