Tapes: Depending upon the materials used, they are classified as:
(i) Cloth or linen tape
(ii) Metallic tape
(iii) Steel tape and
(iv) Invar tape.
(i) Cloth or Linen Tape: 12 to 15 mm wide cloth or linen is varnished and graduations are
Marked. They are provided with brass handle at the ends. They are available in length of 10
m, 20 m, 25 m and 30 m. These tapes are light and flexible.
(ii) Metallic Tape: They are made up of varnished strip of waterproof linen inter woven with
small wires of brass, copper or bronze. End 100 mm length of tapes are provided with leather
or suitable strong plastic materials. Tapes of length 10 m, 20 m, 30 m and 50 m are available
in a case of leather or corrosion resistant metal fitted with a winding device. Red and black
coloured markings are used for indicating full metres and its fractions in centimetres.
iii) Steel Tape: A steel tape consists of 6 to 10 mm wide strip with metal ring at free end and
wound in a leather or corrosion resistant metal case. It is provided with a suitable winding
device. Tapes are marked indicating 5 mm, centimetres, decimetres and metres. The end 10
cm length is marked with millimetres also. 10 m, 20 m, 30 m, or 50 m tapes are used in
iv) Invar Tape: Invar is an alloy of nickel (36%) and steel. It’s coefficient of thermal
is low. Hence errors due to variation in temperature do not affect measurements much. The
width of tape is 6 mm. It is available in length 30 m, 50 m and 100 m. It is accurate but
When the length of the line to be measured is more than a chain length, there is need to mark
the end of the chain length. Arrows are used for this purpose. A typical arrow is shown in
Fig. 12.5. Arrows are made up of 4 mm diameter steel wire with one end sharpened and other
end bent into a loop. Length of an arrow is approximately 400 mm.