Imágenes de páginas
PDF

mortar period made the first recorded milling revolution by using male operatives. These were called ‘‘pounders.” THE QUERN was the first complete grinding machine in which the parts were mechanically combined, and it also introduced the circular motion. It was apparently unknown before 200 B. C., but it was widely used at the dawn of the Christian era, and it is often mentioned in the Bible. The first form of the lower stone was conical, but the later type was flattened. The upper stone conformed to the pattern of its mate. Hollowed out in the centre until there was a hole at its base, the upper stone also served as a grain hopper. The stone was turned by a

THE QUERN, AN EARLY FoRM of ston E MILL

handle inserted in its side. An important improvement was made at an early date when the grinding faces of the stone were grooved, for the edges facilitated grinding and the grooves served as channels through which the meal was forced to the rim of the stones. This was a rude foreshadowing of the principles of methodical furrowing, a process which was not fully developed until the era of water mills. The quern was the original British flour mill, and it is claimed that it was still used in the mountainous parts of Scotland a decade ago. When the quern was large the upper stone had two handles. Women did the grinding. In Homer's time, the millers were also women, and it required the labor of from one-tenth to onesixteenth of the community to prepare flour. Ever since the

[graphic]

making of flour became a distinct trade, milling has been esteemed as an honorable occupation. A sturdy and independent character was always ascribed to the miller, and he and his mill have been a favorite theme with the writers of all ages. Slave and Cattle Mills.-For many centuries the greatest changes in the milling industry were made in the motor power rather than in the grinding process itself. The advent of the quern and its improvements brought the professional miller, who marked the beginning of manorial or village milling. As the quern increased in size it ceased to be a hand mill, and power was applied. At first slaves, and even criminals, supplied the power. A circular piece of wood was placed around their necks, so that they were unable to put their hands to the mouth and eat of the meal. There were also cattle mills which were similar to the slave mills, and for many years in Rome, ‘‘the human animals and their brute companions performed the flour-making of the Eternal City.” Cattle mills increased in number after the abolition of slavery in the fourth century. As early as 1537, treadmills were worked by convicts in Europe. They are still found in some countries, and are the sole survivors of the old Roman slave mills. The slave and cattle mills were supposed to have preceded the water mills, but the latter have existed in northern and western Europe prior to all historic records. They were also found in Greece, and later in Rome. Besides the hand querns, the ancient Egyptians had a larger quern that was worked by oxen. Wind and Water Mills.-In many cases the wind mill appeared before the water mill. In early England wind was utilized to a greater extent than water, and wind mills were in existence at least as early as 1191. With the development of the mill stone, the grist mill appeared. The miller now ground for a larger district, and exacted toll, called “millcorn. '' from the farmers. The mills were generally owned by the lords of manors, who farmed them and their appurtenant privileges to the millers. The water mill was introduced into England at the time of Julius ("aesar. In France, Italy and elsewhere mention of it became common in the fifth century. It was exactly like the hand mill, except that water was used for power. Tidal mills were worked as early as 1526. The water was impounded at high tide, and the mills worked during the ebb. The wind mill seems to have come into use in England about 1200. The first

milling by steam was in England in 1784. The earliest mills in the United States were operated by

horse power, and the toll was higher than at those where water

- - DETAILS OF AN OLD DUTCH WIND MILL

or wind power was used. The first mills of the Red river valley were operated by oxen, or by wind power. In 1870 there were 22 flour mills in South Carolina that were operated by horse power. In Texas there were 50, and 17 more were driven by oxen, while wind furnished power for five. Many of the primitive forms of mills can still be found in operation in various parts of the world. Modern Improvements and Processes.—In the first milling, the entire wheat went into the flour. There was no “bolting’’ or classification of the product by separating it into several grades. Usually not even the bran was separated. The first distinctively modern improvements were in the line of bolting the flour. The primary sieve was an extended bag which was shaken by machinery. Its first introduction was in the power mills at the beginning of the sixteenth century. A German miller seems to have the credit for bringing forth this reel as a flour-dressing device. It was the predecessor of all subsequent bolting apparatus and of all appliances for purifying and separating the various grades of flour. The old Roman system of cylinder milling, which is similar in principle to an ordinary coffee mill, was developed in Hungary. Elsewhere the system known as “low milling’’ was more common. In this the grain was ground in one process between two crushers placed as near together as possible. In the United States the flour making industry was early developed in Pennsylvania, and in connection with this was given the first patent to a citizen of the new world for an invention (1715). A Philadelphia woman invented the device, which was in its essential portion a series of mortars driven by mechanical power. In few industries has there been so much litigation and controversy as in the manufacture of machinery for milling. Many patents for machines with the same object in view were taken out almost simultaneously. In the invention of all kinds of milling machines, competition has been so brisk that it is difficult to determine questions of priority and relative efficiency. New York city and Philadelphia had good bolting facilities even before 1698, but such facilities did not become general until the beginning of the nineteenth century. . Oliver Evans (Philadelphia, 1756-1819) invented the elevator, conveyor, drill, descender and hopper-bag, from which “dates the long period of so-called ‘American’ milling, which produced flour as economically and of as good a grade as that of foreign millers.” There was little progress from the days of Evans

[graphic]

until the introduction of the ‘‘new’’ process about 1870. During the time of Evans, wheat was cleaned with rolling screens and blast fans. About the middle of the nineteenth century smutters were introduced, and a little later, separators, by means of which a more thorough system of wheat cleaning became established. “Low'' Milling.—Before 1850, the millstones in the United States were run at a comparatively low speed, and the grinding was slow. By this date the milling industry had assumed such commercial importance that it was necessary to increase the speed of the stones in order to get the work done. From 1850 to 1875, hard, low grinding was the rule, and the prime object was to make the largest possible percentage of flour at the first grinding. The change in process, due to greater speed, increased the output and improved its quality, ‘‘the outcome being a white, soft flour that met with favor in all he leading markets of the world where American winter wheat flours were handled.” By this process, however, it was impossible to get the flour entirely free from contamination, and some of the bran always remained. There were two parts to this old process, reducing the wheat to flour by passing it through a run of stones, and bolting the resulting material in order to separate the flour from the bran and other undesirable parts of the kernel. The percentage of flour obtained by this single grinding depended on four things: (1) The dress of the millstone; (2) the face of grinding surface; (3) the balancing of upper or runner stones; and (4) the speed of the runner. As there was but one grinding, the making of middlings was avoided as much as possible. By this method of milling, some of the bran was pulverized so that it could not be separated from the flour. This gave the flour a darker color, and caused it to gather more moisture, which injured its keeping qualities, especially in moist or hot climates. ‘' High’’ Milling was the next step in advance. In this the speed of the stones was again decreased, and they were set far apart. This advance was made possible by the middlings purifier, which was not invented in the United States much prior to 1870, although its principle had long been known and applied in Europe. It was a machine for separating the dust, fluffy material, particles of bran, and the flour, from the middlings. It

« AnteriorContinuar »