Gridline Instruments

Gerugambakkam, Chennai, Tamil Nadu

This was the type of chain used by early surveyors to measure distances -- this is where the unit "a chain" comes from. A chain is 66 feet long, 80 chains make a mile. A "rod" or "pole" is 14 of a chain, or 16-12 feet long. Thus "40 rods" is 10 chains, or 18 of a mile.Modern "chains" are actually steel tapes graduated in chains, and are used by foresters to retrace old survey lines. From the Leonard's Mills Forest and Logging Museum.

• FeaturesPrism can be set (1/4" screw) at every 30cm position.

Mini Prism with plastic holder, circular bubble, cw with (4x30cm), pole. Conveniently stored in the instrument container, Mini Prisms offer a high positional accuracy due to their small size. The GMP111 has a built-in leveling bubble and supplied with an attachable spike. With this arrangement a point can be measured with very high precision.

• Size20 cms

Ranging Rods made from best quality conduit pipes. These are socket type and screw type. Each section is painted alternately with red and white paints at 20 cms intervals. Fitted with pointed shoe. International Standard, Automatically processed under strict quality control. High Accuracy, quality, durability and workmanship. Strong High Tensile extruded aluminium alloy. Painted with water proof paints. Brightly coloured for high on site visibility.