San José Gristmill

Outside the north wall of Mission San José, next to the acequia that supplies its power, stands a gristmill. Built around 1794, this mill was the only water-powered mill in the area during the Spanish colonial period. It was not until the end of the mission period in Texas that the Indian neophytes accepted wheat-based products; they move from corn to wheat in their diets. Farmlands were open to its cultivation and a mill was constructed. However, the mill constructed to process this wheat had a short life.

Corn and Wheat

Corn grew easily in the farm fields of the missions. But wheat was the cereal grain most familiar to and preferred by the Spanish hierarchy of the mission. In 1778, orders had been issued that wheat be cultivated at the missions. Previous to 1794, when the mill was constructed, the cultivation of wheat or the presence of a mill had never been recorded.

acequia forebay shaft

How the mill works
Located next to the acequia madre, the mill diverts water to power the mill. Water fills a 9-foot forebay;it is the depth and the constant level of the water that is necessary to maintain a constant speed onto the water wheel below. The water flows from the bottom of the forebay by way of a chute onto the wheel in the wheel room. Water hits the horizontal wheel one blade at a time with enough force to bring the next blade into play. The rotation of the wheel is maintained as long as water hits the wheel. After hitting the wheel, the water flows out of the tailrace and would, traditionally, have irrigated fields or have returned to the San Antonio River.

A wood and metal shaft attached to the water wheel extends up through the floor of the milling room and the bottom millstone. The top stone is then balanced on a metal spike on the end of the shaft. As the water wheel turns, the top stone turns;the bottom one remains stationary. One revolution of the wheel equals one revolution of the top stone. The miller has the ability to raise or lower the top stone to adjust for coarser or finer flour. But at no time should the two millstones touch –the friction could render the flour unusable or cause a fire!

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Dancing Damsel (top) and Stone Furrows (bottom)
Dancing Damsel (top) and Stone Furrows (bottom)

How wheat is ground
Wheat, placed in the hopper, flows by gravity into the feed shoe. The feed shoe is set at an angle that allows most of the grain to slide out. The dancing damsel rides on the top stone and vibrates the feed shoe allowing the grain to fall into the center hole, or eye, of the stone at a regular rate.

Grooves, or furrows, carved in both stones, push the grain to the outer edge of the stones. The furrows are deep and wide in the center and become shallow and narrow at the outer edge of the stones. In addition to them being tapered, the furrows of the top stone crosses the ones in the bottom stone like scissors or shears. By the time the wheat has reached the outside edge of the stones it is wheat meal and can be as fine as face powder. The meal is collected in a box or buckets below the meal spout and then would be sifted to create flour.

Even though the San José mill was small and simple, when operating at full capacity, it could grind one bushel, or 60 pounds, of grain every hour. This was enough flour for 1,000 loaves of bread in one day. Why the mill ceased operation within 10-12 years is a mystery.

Last updated: May 17, 2021

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