Weights and Measures

How do you compare two items? It’s easy if you have both of them to look at. If you have a series of tiles, like the one in the figure, you can see whether they are the same size by simply looking at them. They fit together, so they must be the same size. If the tiles are loose, you can find out whether they are the same size by placing them on top of each other.

Figure 1. Nine-inch (about 13 centimeters) wooden tiles

Now, suppose you need to go to the store to get more tiles, and don’t have any extra to take along. Of course, you would measure the sides of the tile. When you measure it, you would find that the tile was nine inches (or about 13 centimeters) on a side. In the United States, where tile size is still measured in the English system, either “about 13 centimeters” or “nine inches” would be sufficient information to get you the tile you wanted – provided of course you had the right color, etc.

Having agreed-upon standards for measurements of length and volume has always been important for trade. If you need a liter of milk, you can go to the store and know that you are getting a liter. Before people had standard measurements, lengths and volumes were only rough approximations. In the English system, a “yard” was related to the size of a king’s waist, or the distance from his nose to the thumb on his outstretched arm. The cubit, as used in Ancient Egypt, was the length of a man’s forearm, and also related to the width of the palm of the hand or the width of a thumb. The “royal cubit” was 52.4 cm long. Other ancient peoples also used the cubit, but the length varied. For example, the royal Persian Cubit was 64.2 cm long.

For weights, early peoples would put stones on one side of a hand-held balance scale to measure the weight of whatever was being sold. Different sets of stones would be used for different items.

With such imprecise measurements, it was fairly easy for dishonest merchants to cheat their customers.

Even today, some measurements are surprisingly imprecise. The most extreme example I’ve come across is the size of women’s clothes in the United States. I have noticed for a number of years that my clothes size was getting smaller even though my actual size wasn’t.

I illustrate this with a story. About three years ago, when my husband and I went to see our daughter’s graduation from college, we stayed near the home of home one of America’s most famous woolen mills. In 1974, I had purchased a pair of their wool pants, which I loved. Since the cuffs were getting a bit frayed, I decided to take advantage of being near the mill to get another pair, as close to the first one as I could find. And I succeeded. They were exactly the same size except for a couple of details – the newer pants were slightly longer and the legs were narrower at the bottom.

Figure 2. Wool pants purchased in 2004 (left) and 1974 (right). The tiles are nine inches (about 13 centimeters) on a side.

However, the new pants (left in the figure) are Size 6 and the old pants (right) are Size 12. I also purchased a jacket to go with the pants on both occasions. The new jacket is a Size 8; the old jacket is Size 14. And my weight hasn’t changed with time. I still wear both pairs of pants, and both jackets, and they all fit.

I have noticed this with clothing from other manufacturers, but only the recent experience allowed me to buy the same items of clothing from the same manufacturer. So it should not be a surprise that I never buy clothing without out first trying it on.

Can you speculate as to why these clothing measurements have changed? Could it be that the average weight of Americans continues to rise, so that what was once considered a medium size is now considered small?

So, you can see that the measurements of women’s clothing sizes in the United States can cause confusion. They are not “standardized” measurements. Today, there are standardized definitions of what a liter, meter, or temperature is. When you buy a liter or milk, or a meter of cloth, you know exactly how much you are getting. Measurements are really useful only when they mean the same thing to everyone.