Ever watch a caboose rumble past and wonder what those guys were doing in there? Cooking? Playing cards? Arguing politics? Looking out those little bay windows to spot hoboes trying to hop the boxcars? Nope, at least, not most of the time. They were watching forward along the train for wisps of smoke coming from the axle bearings just outboard of the steel wheels. Up until almost the middle of this century grease-soaked horsehair in a box oozed oil to lubricate those bearings, seeping gradually over the loaded surface and providing a sacrificial layer of lubricant to preserve the axle and the bearing race.