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.
The term "micron" is a unit of measurement used to express lengths or distances, particularly in the fields of science, engineering, and manufacturing. It is a unit of length in the metric system and is equal to one millionth of a meter, or 0.000001 meters. The symbol for the micron is "µm," where the Greek letter "mu" (µ) represents "micro," indicating that it is a very small unit of measurement.
Microns are commonly used to measure things at a microscopic level, such as the size of cells, particles, or features on a microchip. It's also used in various industries for precision measurements and quality control, particularly in fields like electronics, optics, and materials science. In some contexts, microns may also be referred to as micrometers.