2.1. Accessories for distance measurement

The various accessories used for distance measurement are as follows:

• Chain/Tape
• Arrow/Peg
• Ranging rods
• Plumb bob
• Abney level

Chain/Tape

• Chain is a linear measuring instrument which consists of interlinked galvanized mild steel wire joined by circular or oval rings. 
• These rings provide flexibility to the chains.

• Tape is a long and thin ribbon or strip of fiberglass, cloth or metal which is used as a tool for measuring linear distances. 
• It is marked in centimeters and inches.

Arrow/Peg

• Arrows are the pins made up of steel wire.
• Diameter : 4 mm
• Length : 25-50cm (40 cm commonly used)
• One end is sharp and another is bent in a loop or circle for carrying.

• Pegs are made up of timber.
• Length : 15 cm
• 2.5 cm to 3 cm square shape in top view.
• Driven in ground with the help of a Mallet hammer.
• Tapered (pointed) at the bottom end.
• Keep about 3.4 cm projecting above the surface.
  

Ranging rods

• Length of either 2 m or 3m.
• It has a heavy iron point at bottom.
• Painted in alternative bands of either black or red and white.
• Its band is 20 cm deep.
• Diameter : 3 cm

Plumb bob

• Made up of iron, steel or other metals.
• Used for centering. 
• Used for taking verticality measurements.

Abney level

• It is a light compact and handheld instrument with low precision as compared to other engineering equipment. 
• It is used to measure vertical angle and slope of ground.