The Technology 

With an undershot water wheel, the wheel is partially submerged into the water, and the force of current turns the water wheel. It was only 35% efficient, but was relatively simple to setup, because it did not require extra infrastructure like the overshot wheel. [16]  (Fig. 2)

“Most of the early water mills were built with as little expense possible on small streams.  The wheel they used, the undershot wheel, was constructed over the stream and turned by the force of the water against its lower blades.  Many of the streams in the beginning came from the woodlands and when the land was cleared of wood the streams either completely dried up in the summer or became too small to turn the mill wheel.” [17]

     The overshot wheel presented a more efficient but more costly alternative.  The water was applied to the top of the wheel, which turned through a combination of the force of the water striking the wheel, and the weight of the water held in its buckets.  The water spilled out after one third of the rotation.  Overshot wheels were 70-90% efficient. [18]  (Fig.3) Because the water supply entered the top of the wheel, some means was required to elevate the water, and to direct it to the mill.  This was the purpose of mill dams and races.  The overshot wheel was most common in Montgomery County, so most mills had a dam.  [19]

            As mentioned earlier, one of the requirements for a mill site (at least one with an overshot waterwheel) was a suitable location for a dam. The steepness of the banks of a creek, along with the elevation of the area around it would determine if it was suitable for a dam. Sometimes the best location for the dam was half a mile away from the mill seat. [20]  (Fig. 4)

Oliver Evans, a millwright and engineer, listed 6 guidelines for mill dam construction in his book, The Young Mill-wright and Miller’s Guide.  This book also advertised Evans’ innovative improvements on the process of milling, which will be discussed later.  His book became the standard 19^th century miller’s handbook.  [21]

“There are several points to be attained, and dangers to be guarded against, in building mill-dams.  1. Construct them so, that the water, in tumbling over them, cannot undermine their foundations at the lower side.  2. And so that heavy logs, or large pieces of ice, floating down cannot catch against any part of them, but will slide easily over.  3. Build them so that the pressure of force of the current of the water will press their parts more firmly together.  4. Give them a sufficient tumbling space to vent all the water in time of freshets.  5. Make the abutments so high, that the water will not overflow them in time of freshets.  6. Let the dam and mill be a sufficient distance apart, so that the dam will not raise the water on the mill, in time of high flood.”

Water was directed from the dam to the mill through the mill race, which was either a directed ditch or a small elevated aqueduct.  The race leading from the dam to the mill was called a headrace, and the race from the mill back to the stream was called the tailrace.[22]  Races were generally three or four feet in width.  In many cases, the millraces and dam structures survive as the only evidence of a mill.  Some millraces were so long, and so far removed from their water source that they show up on a medium-scale map of the county. (Fig.5)

 One interesting historical account tells of a Montgomery County millrace that ran uphill: “On Longdraught Creek, near the ‘factory fie ld’ of the old Clopper estate, are the foundations of an old mill.  Frances Caulfield claims that the head race runs uphill (which it indeed appears to do) and that he was told in his youth, that slaves helped the water up the hill with paddles and buckets.  He did not know what the mill was for.”[23]

            The source of power may have been the same, but the interior structures of a mill depended on what kind of mill it was.  Most common were grist mills and saw mills, which ground wheat and corn, and cut lumber.  Other mills include cloth fulling mills and forges.

          Millstones, the actual grinders of the grain, were precision cut and required constant maintenance; the quality of the flour and meal produced, and thusly the business of the mill depended on them. Several types of stone had long been established as good millstones before the settlement of Montgomery County.  Two examples are Cullin stone, quarried near Cologne, first recognized by the Romans; and stones from La Ferte-sous-Jouarre in the Marne Valley of Northern France.  The French stones were favored because the stone naturally has tiny holes and cracks.  As the millstones were worn down, new cutting surfaces were revealed. [24]  Locally quarried stones, called country stones, were sufficient for cornmeal, buckwheat and rye flour production, where the final product was coarser than wheat flour. [25]

            The mill operation involves two stones stacked one above the other, the runner and bedstone.  The runner was on top, and received power from the mill.  Through the gearing of the mill, it was possible for the runner to spin at 100 rpm, while the waterwheel spun at only 7 rpm.  Cut into the surfaces of the stones were grooves, called furrows, which radiated outward tangentially from the center hole of the stone. (Fig. 6) The furrows pushed the flour slightly outward as the stone rotated; whole grains were poured into the center, and flour was released around the edges after being pulverized between the two stones. [26]  After grinding, the end product had to be sifted and bolted.  The product of the millstones had fine flour mixed in with bran and coarse parts of the grain.  Bolters were a series of cloths of varying knit, which allowed only certain materials to flow through them.  The smallest particles were removed first.

            Saw mills involved a straight blade connected to a crankshaft, which was turned by the waterwheel.(Fig.7)  An early sawmill was capable of producing 1000 feet of boards per day, but was a slow process.  “A sawyer set the log, ran the saw, went and did something else, and came back in a while to inspect the progress.” [27]

            In 1810, a Massachusetts Quaker, Sister Tabitha Babbitt conceived the idea of a circular saw blade after watching men saw wood by conventional methods.  “[she] rigged up a prototype on her spinning wheel.  Within just a few years circular saw blades  were sold throughout the country.” [28]  The diameter of a circular saw blade had to be twice that of the largest logs it could cut, so blades were often 4 feet or more across. 

            In many cases in Montgomery County, grist and saw mills were located together, drawing water from the same mill dam.  Sometimes they were even located within the same building, drawing power from the same wheel.