So, back to the original question about what MOD means. Well MOD is the ratio of the pitch circle diameter (PCD) to the number of teeth. DP for imperial gears is the number of teeth per one inch of pitch circle diameter. So whilst that may well answer the question, it doesn't really help appreciate the size of a gear.
doer. n. 1. a person or thing that does something or acts in a specified manner: a doer of good. 2. an active or energetic person. 3. a thriving animal, esp a horse. (Ëdu Ér). n.
Doek is Dutch for cloth, which was evolved into the English word duck in reference to sail canvas. Duck was typically made from cotton or linen (flax), with some use of hemp. These natural fibers have poor resistance to rot, UV light and water absorption. Linen is stronger, but cotton is lighter. Linen was the traditional fiber of sails until it was supplanted by cotton during the 19th century.