A "span" is a traditional unit of length used for measuring cloth or fabric. It was historically used in various countries, including England, and is based on the width of the human hand or the spread of the fingers. The actual length of a span could vary depending on the region and historical context.
In England, a span was typically equal to 9 inches or approximately 22.86 centimeters. However, it's important to note that the definition of a span could vary from place to place and over time.
In the United States surveying system, an "inch" is a unit of length, but it is not significantly different from the standard inch used in everyday measurements. An inch in U.S. surveying is equal to 1/12th of a foot, just like the standard inch. This means that one U.S. survey inch is approximately equal to 0.0833333 feet or about 2.54 centimeters.
The primary distinction in U.S. surveying is the use of the survey foot, which is defined as exactly 12 survey inches. This slight difference in the definition of the foot and inch in U.S. surveying is used for precise land measurements and surveying work, especially when dealing with large areas of land. However, for most everyday purposes, the standard inch and foot are used in the United States and other countries that employ the imperial system.