David Foreman, age 13, of East Palestine, Ohio, for his question:

What is troy weight?

It is, of course, high time to adopt the logical metric system. Through the centuries, our weights and measures have got themselves into a most bewildering mess. Troy weight originated in Troyes, a French city where the local merchants devised their own system for measuring their goods. During the 14th century, their troy weight system became popular in England and other parts of Europe. Later, several competing systems were banned, though certain limited troy weights persisted to our so called modern age.

At present, troy weight is the standard by which we weigh gold and silver, coins and platinum. The troy pound has only 12 ounces and weighs 5.760 grains. The everyday avoirdupois pound has 16 ounces and weighs 7,000 grains. The troy ounce equals 480 grains, the avoirdupois ounce weighs slightly more than 437 grains.