Steven Prior, age 12, of Winnipeg,Man., Canada, for his question:     

WHY IS LB. USED FOR POUND?

This particular pound is a weight equal to 16 ounces. It is convenient to use abbreviations for common weights and measures, especially when a person is keeping records. Some of these shortened forms obviously are understandable, such as bush. for a bushel and yd. fob yard. But lb. seems quite unrelated to the word pound.

Actually, some of our weights and measures date back to when ordinary folk used English while the scholars used English and Latin. The pound weight was in common everyday usage. But scholars often referred to it by the Latin name libra. And since most of the written records were kept by the scholars, they used a shortened form of libra. This is how lb. came to be the abbreviated form of pound  and the custom persisted through the centuries.