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A Measure of Confusion

By Daniel Hubbard | March 13, 2011

One of those bits of reverse culture-shock that I have experienced since returning to the U.S. after twenty years abroad has to do with measurement. After years of only needing to think about the metric system’s factors of ten, it was time to try to remember all the factors of 3, 4, 6, 12, 16 etc that populate the American system. I love to cook, so I now have relearned that one fluid ounce is 1/32 of a quart or 1/8 of a cup or 2 tablespoons or 6 teaspoons but I had to look up the correct equivalent in cubic inches (1.65). Of course a U.S. dry quart is approximately 1.16364 times larger than a U.S. liquid quart and both are smaller than an Imperial quart, which is used only for liquids as far as I can tell. That explains why the European measuring cup I have shows a quart as being bigger than a liter when I always thought it was smaller. It is an Imperial quart that is marked on it.

Measuring the Old-Fashioned Way

That is nothing compared to the confusion of measurement that one encounters in historical and genealogical research. Land and estate records often contain unfamiliar units. In the extreme cases it may actually be impossible to determine modern equivalents for what was measured. Today, we expect that no matter what unit we have, that there is some way to convert it to the units that we want. One yard is three feet. One meter is one hundred centimeters. Older measurements may or may not work that way. Today, a foot in Springfield, Massachusetts is the same length as a foot in Springfield, Illinois but measurements in the past often had identical names but local definitions. Nevertheless, the reason that the conversion from archaic units to something modern might be impossible is that often measurement was simply thought of differently in earlier centuries. Units might vary so that the value of what was measured was held constant. For example, one unit of good land might be smaller than the same unit of poor land. Land might also be measured in units that reflected effort. Land units might be defined according to how long it took to plow one unit. The furlong (now officially 1/8 of a mile) was once defined as the answer to the question “How long a furrow can an ox plow without resting?” A distance was a furlong if it was one furrow long. What that might mean in modern measurements would depend on the ox, the farmer, the plow and the soil.

I think it was when I was an eighth grader that I first stumbled across this alternate universe of measurement and being young, it seemed all the stranger. I was researching a family in England whose land was measured in bovatts. That required a trip to the Oxford English Dictionary. A bovate or bovatt was the amount of land a man with one ox (a type of bovine, hence bovate) could plow in a year. Plowing was not a continuous activity so this should be thought of as the amount of land that the man and ox could handle during each plowing season. All sorts of things fed into what that amount of land really was. The quality of the soil might make plowing easier in one place than another. The shape of the field made a difference because turning the ox and plow took a significant amount of time. Also, land that was not being farmed might not be counted in this type of measurement. The size of a unit of land might depend on whether 1/3 or 1/2 of it was fallow because that land did not need plowing and so did not contribute to the plowing time. In modern terms, a bovate might be only ten acres or it could be as much as 18 acres, nearly twice as large.

Measuring Our Land

Gunter's Chain

When land began to be thought of as something to be bought and sold, not something held in return for feudal duties performed, it became important to know how much land one held. Surveying became a necessity. The obscure units of measure, the “rod” and the “chain,” come from the fairly obvious names of measuring devices used by surveyors. One would think that the desire to know how much land one owned would correspond to measuring it according to some standard but at least at first that was not true. A chain for measuring in deep forests might be roughly 45 percent longer than a chain used for measuring open country and such things were only recommendations that could vary from one survey manual to another.

The modern definition of the chain in the English speaking world comes from the early 1600’s when Edmund Gunter decided that a chain should always be 4 rods long, using a rod defined as 16½ feet. Besides simply promoting a single standard length for the chain (66 feet) he also specified that the chain should be divided into 100 links of identical length and that rings should be used as markers every 10 links. He managed to combine the traditional ability to divide a unit in half (a chain of 4 rods could be halved twice) and the ten-based system we use for our numbers. As with almost any compromise, there are things that don’t work perfectly. A link is 7.92 inches, not a convenient conversion.

Beyond introducing a standard measurement unit and making to easy to halve and easy to compute because of the powers of ten, there was another advantage. An acre (originally just the amount of land one could plow in a day) could be reasonably defined as ten square chains. That is, a strip of land one chain wide and one furlong (10 chains) deep. It was these advantages that caused Gunter’s chain to gradually become the dominant unit of length in surveying. And that had some odd consequences. In many American cities, 100 foot plots measure 99 feet. In parts of Manhattan, a block from street to street is 198 feet long. Why? Because when a chain is 66 feet and it is divided into units that are 7.92 inches long, it is a lot easier to measure 99 feet (one and a half chains) or 198 feet (three chains), than it is to get that last foot or two included. Then there is the expression “forty acres and a mule.” Why is forty acres such an important quantity of land in America? It is because a forty acre square is exactly 20 chains on a side. It is easy to measure that way.

Standardization of these old measuring units was not instantaneous. Today, just looking at a land record, we cannot tell exactly what was meant by archaic units. The names rod, perch and pole were interchangeable names for the same unit but what they meant isn’t clear. Even two hundred years after Gunter set in motion the process of standardizing the rod and the chain, a perch could mean anywhere from 16½ feet to 25 feet. A perch might also be a unit of area corresponding to a square rod. Forty such perches were called a rood and unfortunately “rod” could be used to mean “rood” making a rod as a unit of area forty times larger than a square rod. To add insult to mental injury, a perch could also be a unit of volume. In that case it represents a volume one rod long, one cubit (18 inches) high and one foot thick. That, of course, makes 24¾ cubic feet. Understanding these measures is a subtle business.

After the American Revolution there was a movement to clean up the the extreme chaos of measurement that existed. First to be attacked was the measure of value. The pound, with its twenty shillings per pound, twelve pence per shilling and four farthings per penny was replaced by a dollar of one hundred cents. There were plans for doing the same thing for measurements other than value, distance for example, but that is a story for later.

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