Gerald Jablonski, age 9, of Rochester, N.Y., for his question:
What is the metric system?
It is an easy system for doing arithmetic. Our numbers grow by tens, and we use the metric system when we count. We would save lots of trouble if we used the metric system for measuring things. Instead, we measure inches twelves and ounces in sixteens. It would be easier to figure if we had 10 inches in a foot and 10 ounces in pound.
It is called the metric system because it is based on the French metre, which we call the meter. This measure is 39•37 inches or a little longer than a yard. In the metric system, size and weight are also figured from the meter. And the metric system uses the decimal system, which is a way of figuring everything in tens.
The meter is cut into 10 decimeters, the decimeter is cut into 10 centimeters and the centimeter is cut into 10 millimeters. There are 100 centimeters and 1000 millimeters in a meter. Ten meters make a decameter, 10 decimeters make a hectometer and 19 hectometers make a kilometer. A kiloneter is i000 meters or about half a mile.
Size is measured by volume. A cubic meter is a square box, one Meter high and one Meter wide on each side. In one cubic meter there are 1000 cubic decimeters and one million cubic centimeters. The cubic decimeter gives the liter, used for measuring liquids. It is a cube measuring about four inches on each side, and it holds one liter of pure, cold water. A liter of milk is a little less than a quart.
The centimeter is about half an inch, and the cubic centimeter gives the gram for measuring weight. The gram is a cubic centimeter of pure, cold water. Two aspirins weigh about a gram, and there are about 28 grams in an ordinary ounce. Ten grams make a decagram, l0 decagrams make a hectogram, 10 hectograms make a kilogram, which equals about two and a quarter pounds.
The metric system was invented in France, and it is used in many countries. It is used by all scientists, for they need a simple and accurate method for weighing and measuring. Scientists use units even smaller than millimeters, grams and cubic centimeters.
In measuring drugs, we can use the milligram which is a thousandth part of a gram. The milliliter is a thousandth part of a liter. A scientist measuring wave lengths may use the micron, which is one thousandth part of a millimeter or the millimicron which is a million times smaller than a millimeter and in one inch there are about 25 millimeters.