How to Invent Everything: A Survival Guide for the Stranded Time Traveler

by Ryan North

charcoal-producing machine. First, gather a bunch of wood logs, stripped of branches and leaves and ideally already well dried in the sun. Use hardwood if you’re looking for fuel charcoal (it burns hotter) and softwood if you want to filter water (it’s more porous, which allows it to absorb more impurities).* Take a 2m-long pole and mount it in the ground—this will be the center of your pile. Using smaller logs—about 10cm in diameter—crisscross them on the ground to make a grid, and extend this grid of logs out until you’ve got a flat and roughly circular area about 4m in diameter around your log. This is your platform. On your platform, place the wood that’s to be turned into charcoal, packed as densely as possible. Longer pieces (up to 2m long) can be placed vertically, leaning against your central pole, with smaller pieces leaning vertically against them. Your goal is to construct a roughly circular mound, rising about 1.5m tall and filled as efficiently as possible with wood, with your 2m-tall post poking out of the middle. Once you’ve got your wood pile, seal it by covering it in a layer of straw or leaves and then adding sand, soil, sod, turf, clay, or other surface materials on top, building a 10-to-20cm layer of this sealant. Don’t forget to leave several air holes at the base of the mound: these are areas you can seal or unseal during burning to control the fire within those particular sections of your pile. When you’re ready to burn, climb up your pile and pull u...