First off, you'll notice they often wet the area right before you start on the coals, or at least do it next to wet grass. In other words, do not get drunk and try these just because this article explained how they're done. For the blocks to break, there must be enough space beneath them for them to bend. But just to be clear: Conversely, you can't run top speed across them because that'll cause your feet to sink deeper into the coals with each step think of the deep footprints you dig when running through sand, for instancewhich will also burn the shit out of you. The coals are usually just burning cinders of wood, and wood has moisture in it. These historical finds don't belong in museums, they belong in horror movies.
Problems tend to arise when your esophagus contracts around the latter, so the entire trick to sword swallowing is to slowly usually over a few years train yourself to control your gag reflex.
Also, if you don't let the coals burn down long enough before you try walking over them, that's also bad news. But let's see this guy kick our asses at Call of Duty. And don't forget to follow us on Facebook and Twitter to get sexy, sexy jokes sent straight to your news feed. Understandably they tend to draw a crowd, because a bunch of nails clustered together isn't the kind of surface that begs to be slept on. The water creates an insulating vapor to greatly reduce heat transference, essentially encasing your feet in a fireproof mist. If the water inside the coals hasn't had enough time to evaporate it counteracts the difference in thermal conductivity we discussed earlier, and once again you're screwed. Certainly not enough to let the nail punch through your skin.