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Bottle Weights, as used in regulating grinding with millstones

Wooden bottle weights from late 1700's and early 1800's Pennsylvania mills.
The upper end of the bottle weight is split and the leather stap is held in place with a pin.

Bottle Weights, as used in regulating grinding with millstones
by Theodore R. Hazen.

To discover about the Cosmic Beginning, you may look in the Bible. In the case of milling, you would look in the Miller's Bible, "The Young Mill-Wright and Miller's Guide," by Oliver Evans, first published in 1795, and running to 15 editions by 1860. Oliver Evans is writing a book describing his improvements in flour milling felt that for proper understanding of the art of milling, he should include sections dealing with the principles of mechanics and hydraulics, a section on the state of the art of building mills, and on manufacturing grain into flour. Mill-Wright, Thomas Ellicott, added his practical instructions for building mills. This section deals with tentering, and the use of the lighter staff and bottle weight in that process. Turning to the pages of Evans book, we read, "The lighter (staff) is fixed in front of the mill-beam, at such a height as to be handy to raise and lower at pleasure; a weight of 4 lbs. is hung to the end of it by a strap, which laps two or three times round, and the other end is fastened to the post below, that keeps it in its place." This weight is called a bottle weight.

The lighter staff is used for raising and lowering the runner stone. Its called the lighter staff, because its movement lightens the grinding effect of the millstones upon the grain. Raising and lowering the lighter staff, a term called tentering, adjusts the distance between the millstones for the desired type of grind. The bottle weight is then what holds the lighter staff in position to maintain uniform result.

Other than in drawings found in his book (often reproduced elsewhere) there is no further mention of how this weight is used. Yet, the weight is a mill feature that is not widely understood or even recognized when taken away from the mill. Most people who try to read Evans book become baffled and soon there after are totally lost. They don't realize, you need some understanding of mills before you can make any sense of this important guide to milling.

As Mr. Evans considered himself a practical man, and put together a useful book for the mill-Wright and miller. Oliver Evans book is also the first technical manual for the miller and mill-wright. up until his time information was passed on through the apprentice system. So if there had been a complete guide before Oliver Evans, it would have given the method of tentering millstones by the use of a lighter staff. Tentering is the term used in adjusting the distance between the millstones, to produce finer or coarser four and meal. In a traditional or pre-Oliver Evans mill, the millstones are set up on the millstone floor. This may not be the first (main) floor. In some mills, the millstone floor may be on a platform or sub-floor, just above or below the first (main) floor. The miller only need go there to either fill the millstone's hopper with grain, or to dress the millstones. The miller's primary station in this traditional type of mill, is on the level below, which is most often in the mill's basement. Where the flour comes out from the millstones, there you would find the miller at work. The problem with the miller being in the basement is his health. It's cold and damp there, and the light is poor. Here the miller had to learn how to judge the quality of his grind by touch and feel. With the miller in the basement are the control devices he used to run the mill.

These adjustments include a number of traditional methods, such as the twist peg and its crook string. The crook string goes up through the floor to the vat (millstone cover) and is attached or goes through the wooden shoe. Sometimes the end is attached to a wooden ash spring called the "millers willow," which provides tension of the shoe against the damsel. By turning the twist peg, one way or the other, he can make an adjustment in how much or how little the grain is fed into the millstones. The damsel is attached to and turn with the upper stone forcing the shoe to shake at a constant rate, which insures it's always a constant amount. The other device found in the basement with the miller is the lighter staff. The lighter staff is most often a square or rectangular length of wood. In later years, it might be a threaded iron rod and called a tentering screw. It is connected to the linkage by a pin, down to the bray. The lighter staff is most often straight, or it may have a slight curve to it. The opposite handle end of it is rounded for the miller's hand and to wrap around a leather strap. It is wrapped around several times and turned over its self. One end is attached to a beam which is part of the husk frame. While the free end from the fold is connected to the (bottle) weight. This keeps the lighter staff in its desired position once the miller had set the type of desired grind.

When the mill is stopped, normally the runner stone would be resting on the lower bed stone, and most often, with a cushion of grain between the two millstones. The cushion of grain act as a buffer to keep the millstones from being damaged or creating sparks. The combined weight of these two millstones maybe two tons or more. This is enough to counter act the weight of the water. To start the mill, the miller needs only to lift (or separate) the upper millstone from the bed stone. With the runner stone mounted on the millstone spindle, the spindle sits in an open bearing, approximately in the middle of the bridge tree (the long beam below the millstones). One end of the bridge tree is hinged to the husk frame in a vertical slot. The opposite end can be raised or lowered, by the bray, which is the short beam below one end of the lighter staff, thus creating a compound lever. Making it very easy to raise the weight of the runner stone. then the miller with very little effort pulls down the lighter staff, raising the runner stone. For just a moment the runner millstone stays there, motionless, until the weight of the water takes over and starts turning the water wheel. All at once the gears and the runner stone also turn. In this traditional type of a mill, the water controls may also be in the basement. they may come through the mill's outside wall, or down from the floor above.

If the miller's millstones are properly level and balanced, the mill should run all day without any further adjusting. From this point on, the miller may no longer need to touch the handle end of the lighter staff. Tentering or adjusting the grind or changes in it maybe made through the leather strap and the bottle weight. To lighten or to make coarser the grind, the miller needs only to pull down on the leather strap, just above the bottle weight. If the miller desires to bring the millstones closer together and make the grind finer, the miller needs only to tap lightly upwards on the bottom of the bottle weight. If the leather strap is wound several times around the handle end of the lighter staff and folded over its self properly, it should hold tension through the changes in adjustments.

Simply the bottle weight keeps the tension on the strap. By lifting the weight, the strap will slide which in turn raises the lighter staff, bring the millstones closer together.

Bottle weights are a very fragile part of the mill. The strap rots and needs to be replaced. In an abandoned mill, a rotten strap may cause the bottle weight to fall off, or be carried away in a flood. If the end of the strap is nailed or tacked to the bottle weight, during normal mill operation, the nails or tacks may come loose from the wood. Often when the miller is making adjustments to the millstones, the nails or tacks will slide through the miller's palm, as the bottle weight falls to the floor, or into the gear pit. Some millers have gotten disgusted and given up with the strap and bottle weight. Instead they have nailed up a board with holes in it, often called a "back board." A back board has a series of diagonal lines of holes in it. The miller can pull down on the lighter staff and hold it at its desired position with a pin or blot. This is a poor solution, the miller may lose the lighter staff handle in setting the bolt, causing the millstones to suddenly come together. No matter how the holes are positioned, there maybe some place where there is no hole for the desired position for grinding. It seems it might have been better to keep what was there in the first place- the bottle weight.

Soapstone bottle Weights attached to a leather strap wrapped around the lighter staff,
which controls the spacing between the millstones. A wooden or stone bottle weight
weights approximately four pounds, and is just enough to put tension
on the leather strapwhen wrapped around the lighter staff.
This process of adjusting the spacing is called Tentering.
The mill's basement of the Newlin Grist Mill, Glen Mills, Pennsylvania.

The stone bottle weight with a hole in it maybe a better alternative to the tacks in wooden bottle weights. The leather strap is placed through the opening and folded over with a rivet. An old wooden bottle weight has a number of old tack holes in it, or even where it was screwed on. The holes show it may have been reattached a number of times when it fell from the strap or when the strap needed replacing. A hollow bottle weight was found in the mud below the water wheel at the Burwell-Morgan Mill, Millwood, Virginia. The end of the strap is inserted down the hole of the neck of the bottle weight and is held in place by a curved wooden key. The metal collar keeps the top of the bottle neck from splitting.

Sometimes bottle weights are simple round bottle shaped pieces of wood. Plain simple lines or with a great deal of skill going into embellishing the turned bottles. The millwright put his own identity into his own pattern of how he shaped and purposely finished the bottle weight. One millwright's way of attaching the leather strap was to split the top of the wooden bottle. So then he inserted the end of the strap by sliding it into the slot. It was held in place with a dowel pin through the split ends,, and in the leather passed through by the dowel pin. Thus making it look finished as of the leather transforms into the bottle weight.

Look to see how the miller tentered his millstones and if you don't see a lighter (tentering) screw and hand wheel, look for the lighter staff and bottle weight. If it is original, it may too reveal some of the millwrights handy work and skill. Then all of his efforts won't be forgotten. Often when found elsewhere, far removed from the mill for which they were made, the bottle weight becomes a curiosity. Lost are the millwrights skill and identity that went into each one. People come across them and are ignorant of bottle weights and invent possible uses for these turned pieces of wood. Some think that they were a pattern used in making glass bottles! The weights used elsewhere in the mill are metal, used on the hopper boy, sack hoist, doors. they look like weights, bottle weights don't. The wooden bottle weight is the way it is because a turned wooden bottle shape is 4 lbs. in weight. This is just the right amount of weight to put tension on the leather strap. A metal weight on the other hand may not hold the lighter staff in place and tend to pull it down. I have used bottle weights in mills, and I have looked at the Oliver Evans traditional drawing, with the lighter staff and bottle weights. A lot was left up to the young imagination. I do remember thinking years ago, how did this device work?

A Wooden Bottle Weight with a Metal Collar Ring where the Leather Strap end fits inside.
The leather strap is held in place with a round wooden wedge.
This one was found in the gear pit at the Burwell-Morgan Mill, in Millwood, Virginia.

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Copyright 2000 by T. R. Hazen