were also often simply called "powers", unless specification of the type was needed, in which case terms such as "tread power" or "sweep power" were used. Regional norms determined which term was more common in any given region or country. The application or implement being run by the sweep power was often a feed mill or flour mill positioned right at the center, which meant that either no transmission at all was required (the hub of the wheel being also the output shaft) or at most a simple set of gears to step up the RPM for some applications. Transmitting the power output to an application or implement at a distance was accomplished through a shaft that today's typical terminology would call a drive shaft but that was usually called a tumble shaft at the time, at least in North America (sometimes tumbler shaft or tumbling rod). It was also sometimes called a jackshaft, as in many applications the tumble shaft and the countershaft (jackshaft) were one and the same rather than separate components. Terminology was variable, as it was natural based on the logic of the instance. Words like "engine", "mill", "wheel", and "power" were all used as needed. Thus one article that talked about "jack wheels" was referring to the flat-belt pulleys on the tumble shaft that served as countershaft pulleys. Wendel (2004) provides contemporary drawings from advertisements. Power output was limited by the size of the team. Horse powers were often run with a single horse or a two-horse team, which means that, judged by today's standards, not much power output was available and the feed mill or pump being driven was a rather small one. Regarding choice of type, at various times and places there were accepted notions of conventional wisdom, such as that more usable power per horse came from a tread power than from a sweep power (in other words, that a sweep power was less efficient of the horse's effort) or that a tread power would wear down a horse prematurely (a notion roundly refuted by others). Whether or not the efficiency notion was true, sweep powers were simpler and less expensive, so they remained popular. Some were 4-horse designs. Large sweep powers could make use of 6 to 12 horses, but not many family farms could muster that sort of arrangement. It is also true, however, that they had little need for