Nail (Cloth)
A nail is a traditional unit of length used in cloth measurement, equal to 2¼ inches or approximately 5.715 centimeters. It was commonly used by tailors and fabric merchants in England to measure small lengths of fabric.
The term “nail” likely originates from the practice of marking lengths on a measuring stick with notches or nails, making it easy to measure fabric quickly. The nail was a convenient subdivision of the yard, with 1 yard = 16 nails.
Though obsolete today, the nail remains an interesting part of historical textile measurement systems.
Summary:
1 nail = 2¼ inches (5.715 cm)
1 yard = 16 nails
Used historically in tailoring and fabric trade
Originates from notches or nails on measuring sticks
Exameter
An exameter (Em) is a very large unit of length in the metric system. It equals one quintillion meters (1 exameter = 10¹⁸ meters). Exameters are used mainly in astronomy and physics to describe enormous distances, such as those between galaxies or across the universe. Because this unit is so huge, it’s not used for everyday measurements. The exameter helps scientists talk about the vast scale of space in a simpler way.