The first mill was a hole made in a stationary rock (Fig. 1). The grain was placed in the hole and crushed with a stone held in the hand. On Centre street in Trenton, New Jersey, not many years ago one of these primitive mills could still be seen and there are evidences that such mills once existed in all parts of the world. In those places where the earth did not supply the stationary rock, stones were brought from afar and hollowed out into cup-like form and in these the grinding was done.

The mill which consisted of a hole in a rock and a stone in the hands was followed by the "knocking-stane" and mallet (Fig. 2). The "knocking-stane" was a mortar, or cup-shaped vessel made of stone; the mallet was usually made of wood. The grain was placed in the mortar and struck repeatedly with the mallet, the beating being kept up until a coarse flour was produced. This is an exceedingly rude method of crushing grain, yet this is the way the people in some parts of Scotland grind their barley at the present time.

At a very early date the "knocking-stane" was laid aside for the mortar and pestle (Fig. 3) almost everywhere. In this mill the grain instead of being struck with a hammer was pounded with a pestle. The bottom of the pestle was frequently covered with iron in which grooves were cut. As the man pounded he found that when he gave the pestle a twirling or rotary motion as it fell it ground the grain much faster. We may be sure that after this was learned the twirling motion was always given.

The mortar and pestle were followed by the slab-mill (Fig. 4). Here the grain was ground by being rubbed between two stones. Dr. Livingstone, the great African explorer, gives the following description of a slab-mill which he saw in operation in South Africa. "The operator kneeling grasps the upper millstone with both hands and works it backwards and forwards in the hollow of the lower millstone, in the same way that a baker works his dough. The weight of the person is brought to bear on the movable stone and while it is pressed and pushed forward and backward one hand supplies every now and then a little grain to be bruised and ground."

As we have seen, the primitive miller gradually learned that the pestle did better work when it fell with a twirling motion. This little bit of experience led to important results in the development of the mill. If the grinding were done better with a twirling motion, why not have as much of the twirling motion as possible? Why not make the upper stone go round and round? This was what was done. The upper stone was caused to turn round and round. The wheel-mill, the mill of the upper and nether millstone (Fig. 5), was invented. When and where it was invented we cannot tell for it was in use among all civilized peoples before history began to be written. There were many kinds of wheel-mills among the nations of antiquity and in principle they were all alike in construction. How they worked may be learned by studying Figure 5 which represents a mill used in ancient India. The upper stone is placed upon the pivot projecting from the center of the lower (nether) stone, and caused to revolve by means of the handle. The grain when placed in the hollow at the center of the upper stone (Fig. 5) works its way down between the stones and comes out at the circumference ground, bran and flour together. The mill was fed with grain by the operator. The first hopper was a human hand.

We have here several pictures of ancient mills. Figure 6 is an ancient Jewish mill. As we look at it we may recall the words, "Two women shall be grinding at a mill, the one shall be taken, and the other left."14 Figure 7 is an old Roman mill bearing a strong resemblance to the coffee mill that is used in our kitchens. Figure 8 is a Scottish quern, a mill that may still be found in use, it is said, in some parts of Scotland. Figure 9 is an old flour mill dug from the ruins of the city of Pompeii which was destroyed by an eruption in the year 79 A.D. Figure 10 shows the construction of this interesting mill. The upper (outer) stone is shaped like an hour-glass, the upper half of which serves as a hopper; the lower half turns upon the cone-shaped lower stone and does the grinding. The mill was operated by the projecting handles, the operators walking round and round the mill. Sometimes it was turned by human power, sometimes by horses or oxen.

The Pompeian mill shows that as early as the first century the Romans ground their grain by animal power. Indeed about this time a still greater change was made in the method of grinding grain. When Julius CÆsar flourished (50 B.C.) men began to harness the power of running water and make it turn their mills (Fig. 11). From Figure 12 we may easily learn how this was done. The running water turns the wheel and in doing so turns the upper millstone. A hopper is suspended from the roof by ropes. Through this the grain passes into the mill. Here was a great saving in human labor and a great advancement in mill making. A Roman writer of CÆsar's time appreciating how great a blessing was the invention of the water-mill exclaimed:

Nothing can be simpler than the water-mill described above; it was the old mill of the upper and nether millstones, the old hand mill turned by water. That was all. Yet, as simple as it was, many centuries passed after its invention before a new principle in flour making was discovered. There were inventions for lowering and raising the stone so as to grind finer or coarser as might be desired, and there were improvements in the kind of water wheels employed, and better methods of sifting the flour from the bran were discovered from time to time, but the water-mill invented in the time of Julius CÆsar remained practically unchanged until the early part of the nineteenth century, when the last step in the development of the mill was taken.16

About 1810 millers in Austria, more particularly those in Vienna, began to grind their grain by passing it between two horizontal rollers (Fig. 13). The rollers were spirally grooved and turned toward each other. There was a wide difference between this process and the one to which the world was accustomed, yet the new method was found to be better than the old one. Austrian flour and Austrian bread became famous. The delicious Vienna bread on our tables of course has never seen Vienna. It is called "Vienna bread" because it is made out of a kind of flour which was first ground in the Austrian capital. The Austrian way of grinding grew rapidly into favor among millers everywhere. In the United States where there was so much wheat to be ground the roller process was taken up eagerly and improved upon as only Americans know how to improve upon an idea. In the flour mills of the West the grain was soon passing through a series of rollers. By the first pair of rollers the grain was simply cracked into pieces somewhat coarse. Then after being bolted (sifted) it was passed between a second pair of rollers and reduced to a greater fineness. Then it was bolted again and passed between a third pair of rollers. The rolling and sifting continued until a practically pure flour was obtained. A pure flour is the modern miller's ideal. He wants a branless flour and a flourless bran. The old stone mill could not grind this kind of flour. Before the roller mill appeared there was always bran in the flour and flour in the bran.