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Millstones, An Introduction,
Notes by Charles Howell

An Introduction
Notes by Charles Howell

The grinding of grain by primitive hand stones can be traced back even further than recorded civilization, although the methods used in prehistoric milling are a matter of some conjecture and speculation. It is certain, however, that stones used for grinding grain have progressed through the centuries, from the small stones held in the hand which were used hammer-like fashion to pulverize grain against larger stones or a rock face, to the highly efficient power driven millstones that are still used to this day.

Geologists and archaeologists have come across primitive types of pounding stones of a similar shape in various parts of the world. It is interesting to note that the methods used to reduce grain or berries to a more edible form did not very much by the people in the early civilizations of the Old World, the original peoples of the New World, or by the aborigines of modern uncivilized countries. A similar kind of hammer stone appears to have been in universal use perhaps between 25 and 50 thousand years ago.

The improvements in the simple pounding methods came with the introduction of the mortar and pestle which gave more of a grinding action. The grain was placed in a bowel-like piece of rock, the mortar, and ground by the pestle, a club-shaped implement. This was held in the hand and worked up and down striking the grain. The same principle was also used with mortars fashioned from a section of a hardwood tree trunk, the grain being pounded with hardwood pestles. There were, of course, many variations in the kind of wood used and in the size of the mortars and pestles. The design largely depended on local timber availability and the needs of the people using those grinding implements.

From the primitive hand stones, mortars and pestles, was developed the saddle stone or saddle quern. This device had a saddle shaped stone base, a true grinding action was produced by working a rubbing stone, shaped almost like a rolling pin, back and forth across the abrasive surface of this stone base, on which the grain was scattered. Later improvements to the saddle stones were, having the milling surfaces of a flat base stone and enlarged flat rubbing stone grooved so that the grooves crossed each other to improve the shearing action. This grooving of these early grinding stones, must have been one of the first steps towards a definite pattern of millstone dressing. To assist in the operation of the larger rubbing upper stones, handles were fitted at either side of the rubbing stone, so that more force could be used in a push and pull motion. This type was called a push mill. In later larger versions levers were fitted so that the whole of the force of the operator's body could be utilized. This improved type of mill was sometimes termed a lever mill.

About two hundred years B. C. rotary motion came into use, this was a great improvement and was first developed by the Romans. One of the early rotary devices was the hourglass mill, or conical quern, in which the upper stone was suspended over the conical shaped lower stone. The top portion of the upper stone was hopper shaped and used to feed the grain through a perforated iron plate fitted in the center of the two sections. This iron plate, called the rynd, had a central socket eye which was pivoted on top of a spindle fixed into the lower stone, so that the upper stone did not rest directly on the lower one. The upper stone was turned by means of bars projecting from its side, the operator or operators, walking round the mill. The grain from the revolving hopper gradually fed through the space between it and the lower, producing coarser meal; while a thin shim, by bringing the stones closer together, would produce finer meal. This method of adjustment, although effectual, was most troublesome, as it involved the lifting off of the top stone every time a change in the texture of the meal was desired. The later bridge-tree method is much easier and more effective. To turn the upper stone, a wooden handle is inserted in the top surface of the stone, so that when grinding, the upper stone revolves and the lower stone is stationary. The grain is fed in through the eye, radiated from the center of the stones and is ground into meal by the action of the upper stone passing over the lower one, the meal emerges all round the periphery of the stones.

Animal power was also utilized to power the larger versions of the quern. Even today, primitive methods of grain grinding by camel, donkey or oxen power are found in India, the Middle East and many other countries.

The quern proved to be the only one out of all the ancient hand stones used, to survive amongst the majority of the civilized nations. One exception being Mexico, which in her present civilization still retains the Metata, which is rather an elaborate kind of saddle stone. In remote areas of Mexico, the traveler may still witness the grinding of corn by the women of the household, using these ancient grain stones. Possibly every country in the Old World has used, or still uses, the Roman quern. In North and South America and in Southern Africa the quern does not appear to have been used. When the Western Hemisphere was discovered, the grinding of grain passed directly from the pestle and mortar method, to millstones powered by water wind and perhaps in isolated cased by horse or oxen power. Some of the early colonists did however bring small quern type mills with them from Europe and there were possible a few querns fashioned by the settlers in North America before power mills were erected.

From the quern was developed the millstones that have been used in power driven mills for hundreds of years. The principle of the upper stone revolving, the runner, and the lower stone stationary, the bed stone, was the method most commonly used. One of the variations is, the upper runner mill, in which, the upper stone is suspended in a fixed position in a wood or iron frame. The lower stone revolves keyed or fastened into a spindle, which is adjustable vertically so as to determine the texture of the meal as in the application of the upper runner mill. Another type of grain grinding machine is fitted with vertical stones. This machine was developed to a high state of perfection in the late 19th century, the frame of these mills is often made of cast iron. The stationary stone is in a fixed position, the runner stone is keyed to a horizontal shaft which is usually driven by flat belt drive. The drive shaft is adjustable end ways by a hand wheel on a screw attached to a thrust bearing, this alters the space between the stones so that the particles size of the ground product can be varied. The thrust bearing is spring loaded, this allows the stones to open, should any foreign bodies, such as pieces of tramp iron, enter with the feed, thus preventing damage to the stones. The two stones are enclosed in a round case, almost like the a drum, the grain is fed in between the stones through a hole in the upper center part of the stationary stone. The meal emerges from the periphery of the stones and falls out at the bottom or side of the drum like case down an attached spout. The runner stone has flat iron sweepers fitted on its edge, these have a two fold purpose; to keep the case clear of ground meal and to balance the stone.

In all the early mills, the material of the millstones depended on whatever hard stone could be obtained locally. Transport of heavy stones was, of course, difficult, so that any suitable local stone was used. The Romans seem to have been the first people to move stone for milling purposes an y great distance. From the well known Andernach quarries in the Rhine Valley, Germany, the Romans shipped quern and mill stones to most parts of the European Continent. This stone is a blue black lava, commonly called "Cullin" stone. Cullin is a corruption of the name of Cologne, from which city this stone was shipped down the Rhine. The millstones produced from Andernach stone, were called Blue Stones, Rhine stones, Cologne stones and Holland stones. Quarries in Germany are still producing millstones at the present time.

The best and most popular stone ever discovered for grinding wheat into white flour is the French Burr. This stone is a freshwater quartz and was quarried at La Ferte sous Jouarre near the town of Chalons in the Marne Valley in Northern France, the stone from this district became world famous. The remarkable thing about this stone from La Ferte sous Jouarre was that it was only found in small pieces ranging from about 12 to 18 inches long, from 6 to 10 inches wide, by 5 to 10 inches thick, usually embedded in layers of clay. There were sometimes pieces of a larger size, but none large enough to make a complete millstone of the usual size 4 feet to 4 feet, 6 inches diameter, so that the French millstone of popular size, had to be built up. One reason why French stones were so successful was their high percentage of porosity. Some pieces were simply a mass of porous cells and as the stones wore away, new cutting edges appeared which could be worked without being refaced or redressed. Other pieces of La Ferte sous Jouarre stone were extremely hard and of close texture. The more porous pieces of stone were often light brown in color and called "nutmeg" burrs. The hard, close textured pieces were usually of lighter color and called "white" burrs. French stones produced a whiter flour from wheat because the extremely hard nature of the stone was far less abrasive than any other stone used. An abrasive stone tends to shred the outer part of the grain of wheat, the bran, into a powder. This fine powdered bran dresses through the fine mesh silk or woven wire of the flour dressing machinery or bolters together with the white part of the wheat meal and the flour thus produced is of a darker color.

In the heyday of millstone milling, there were hundreds of firms of French millstones makers, and these people imported vast quantities of the La Ferte sous Jouarre blocks of stone into their respective countries. Even today, it is still possible to have new French millstones manufactured. The process of building the complete millstones from the blocks of rough stones, begins with selecting suitable pieces so as to form, usually two concentric rings looking rather like keystones of an arch. The number of sectional pieces used, varies, depending on the size of the blocks; some French millstones have as many as nineteen sections, while there are others with as few as four sections. Where there are two rings of stone sections, a good millstone maker will select the harder burrs for the outer ring and the softer burrs for the inner ring. This selection of stone is to allow for the extra wear on the outer ring as, of course, the periphery of the runner stone travels much faster than the center and also covers a larger area of grain or material contact. Apart from this obvious consideration, the area round the center of the stone, the eye, has to be slightly farther apart than the outer edge of the stones to allow the grain to enter between the stones. This "dishing" of the stones was also known to some millers as "bosoming." The sections of the stone are trimmed and dressed so as to be a good fit and form a perfectly round, solid millstone. The runner stone has a round hole in the center, usually about 10 inches diameter to form the eye, through which the grain is fed. The bed stone is built with a square hole in the center about 10 inches across, this is to accommodate the neck bearing of the driving or balancing spindle. The pieces of stone are cemented or plastered together and bound with iron bands to prevent bursting when the millstones are in use. These bands are usually "sweated" or shrunk on, this is to say, that the iron bands are heated to a red hot condition and thus expand. In this red hot condition the bands are driven over the edge of the stones and as the bands cool they contract to become extremely tight. The top of the runner stone is usually finished off with a layer of plaster of Paris, which is sometimes mixed with small pieces of stone and smoothed off to form a slightly convex top. This plaster of Paris finish also helps to increase the weight of the runner stone and is a saving in cost of the expensive imported stone, if this has to be used to increase the weight. When new, a French runner stone of 4 feet to 4 feet, 6 inches diameter is usually about 12 to 15 inches thick at the circumference, which is known as the "skirt" of millstones, and 15 to 18 inches thick at the eye or center. The weight of these runner stones is upwards of 2,400 pounds. To balance the runner stone when pivoted on top of the spindle, pieces of iron or lead are driven or fastened in appropriate points so as to correct the balance. From about the early nineteenth century, some makers fitted balance boxes, usually four in number which were let into the top of the runner stone at opposite points near the rim, weights could be placed in these boxes to correct the balance. In England, a firm of millwrights, Messrs. Clark and Dunham, patented a special cylindrical balance box which carried lead discs on a screw, these discs could be screwed up or down to balance the stone on both its vertical and its horizontal axis.

The French bed stone has the underside smoothed off to a perfectly level finish with a layer of plaster of Paris, so that the stone will lie flat on its base. To correct any uneven wear, the bed stone would be leveled by using wooden wedges driven under the stone in the appropriate spots. In late nineteenth century mills, bed stones were often set in cast iron "pans," in the base of these pans, usually at four opposite points, were set pins which were adjustable to correct the level of the stone.

In England, in southwest Yorkshire and the northeastern perimeter of Derbyshire, was found an excellent rock for manufacturing millstones. This type of rock is appropriately known as Millstone Grit. Known to British millers as "Peak" or gray stones, they were widely used in the grain milling industry until about sixty years ago. However because of their abrasive nature they were not too suitable for producing white flour from wheat. Quite a number of Peak stones are still at work in the British Isles at the present time, some for grain milling and others are used for special purposes, such as grinding material for the chemical and paint industries. After French millstones became so popular for flour milling, the Peak stones were used for grinding coarse grain for animal feeds, shelling barley and hulling oats. Peak stones were exported to several countries, including the U. S. A. Today, there can be seen hundreds of complete and incomplete Peak millstones scattered about near the old quarry workings, which are mostly situated in desolate moor land districts.

In the United States, the early mills were mostly equipped with stones brought in from Europe. The Cullin stones were very popular, there are many examples of these millstones at early mill sites, particularly near the eastern seaboard. French millstones were used throughout the U. S. A. manly for grinding wheat flour and corn meal particularly after about 1750. There were many firm engaged in importing the blocks of the French stones, and making these blocks into complete millstones, was, for many years, an extensive industry. The advertisements by some of these millstone makers, in the American milling trade journals, claimed that they had their own men in constant attendance at the quarries in France. By having this personal supervision over the quarrying, the makers stated that, only the very best quality burrs were selected for use in their millstones. A few of the firms engaged in building French millstones in the U. S. A. are listed as follows:

In 1774. James Webb, Little Queen Street on the North River, New York City.

1791. G. Speth, New York.

1796. Samuel Wilson, 40 Cortland Street, New York City.

1797. Oliver Evans, 126 South Second Street, Philadelphia, Pa.

In Leffel's Illustrated Milling & Mechanical News, January 1876, there were advertisements by the following millstone makers:

Edward P. Allis & Co., Reliance Works, Milwaukee, Wisconsin.

Samuel Carey, No. 7 Broadway, New York City.

William H. Dillingham, 143 Main Street, Louisville, Kentucky.

Nordyke, Marmon & Co., Richmond, Indiana.

Straub Mill Company, Cincinnati, Ohio.

A Mill Thrif and Mill Bill

There were many sources of native millstones in the American continent, however, no stone had ever been discovered to equal the French Burr stone and in most American mills, French stones would be found in addition to native stones. From Mount Tom, which overlooks Connecticut Valley, came the quartz shot sandstone millstone for the early settlements in that area. Across Long Island Sound in Long Island, many of the mills there also used stones from Connecticut.

In New York State, millstones were quarried at several locations. A few complete and incomplete millstones can still be seen at the old quarry working in an area known as the Traps, near High Falls in Ulster County. The stones from this area were known as Esopus millstones and were cut from deposits of Shawangunk Conglomerate Grit. The Esopus Millstone Company, who were successors to the Bell Millstone Company, had their headquarters at No. 8 Wall Street, Kingston, New York. In advertisements in the milling trade journals, they described their operations as:

Manufacturers of the Well-Known Esopus Millstones. Runners, Beds, Rollers, and Chasers. Blocks for Glaze Pans, Paving and Color Mills and other kinds used by Millers, Mill Manufacturers. Paint and Chemical Mills. Potteries and China works.

The granite from the well known quarries at Westerly in Rhode Island and from quarries in New Hampshire provided many of the stones used in New England mills. One of the largest collections of millstones in New England, can be seen at Millstone Manor, a private house in Shore Road, Ogunquit, Maine. Here, there are reputed to be more than seventy stones as used for grain grinding and other industrial processes. A type of stone similar to the French Burr was discovered in Arkansas in about 1870 but does not appear to have been extensively used. There were millstone quarries at Bowmanstown, Carbon County, Lancaster County and Berkshire County, all in Pennsylvania. Near Marietta in Ohio, a suitable kind of stone for milling purposes was quarried for many years. Quarries were also worked to produce millstones in Virginia and a quartz bearing granite was used for millstones from quarries in Rowan County, North Carolina. In fact, there were probably millstones quarries in most areas where there was a suitable hard stone and where grain milling was carried on to any extent. The size of these native millstones varied from less than two feet and up to seven feet in diameter. When new, these stones would vary from about eight inches to thirty inches in thickness and the largest stones would weigh more than 3,500 pounds.

In modern times, millstones are made of artificial stone. Emery type grit of a varying texture is mixed with a special kind of cement and poured into molds, which are, of course, of any desired size. These modern millstones have many advantages, notably, that they are always sharp; when dressing is required, only the furrows have to be deepened and the area around the eye faced off a little. The output of these stones is also considerably higher for the amount of power consumed. In England and on the European continent, there are still a few firms which still do a fairly extensive business in the manufacture of these modern millstones.

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