About Lesson
Chain
- Composed of 100 or 150 pieces of links, made up of 4 mm diameter galvanized mild steel wire.
- The ends of each link bent into a loop and connected together by means of three oval rings which offered flexibility to the chain and make less liable to become kinked.
- The joints of the links are usually open, but in the best chains they are welded so as to render the chain less liable to stretching.
- The ends of the chain provided with brass handles for dragging the chain on the ground, each with a swivel joint, so that the chain can be turned round without twisting.
- The length of a link is the distance between the centers of the two consecutive middle rings.
- The end links include the handles. Metallic tags or indicators of distinctive pattern are fixed at various distinctive points of the chain to felicitate quick reading of fraction of a chain in surveying measurements.