Pillars and timbering: the ground-support law of the mines of New Spain

The mining ordinances of New Spain left standing pillars of the richest ore and forbade the owner to take them. The 1761 commentary explains why: the pillars hold the roofs, carry the ladders, catch a falling man and let the air move, and justices must inspect the timbering because neglect of it is "en perjuicio de la vida de los Operarios". The same pages record the conflict of interest — the pillars were of the best metal, and the workmen knew how to rob them.