Theory question 202
Surveying(a) Describe the surveyor's chain (b) Outline any three problems that could be encountered in the use of the surveyor's chain.
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(a) A measuring chain made of 100 links of thick steel wire joined by small rings; Gunter's chain is 66 ft (20.1 m) long, the engineer's chain 100 ft, and the metric chain 20 m or 30 m; brass handles at both ends; brass tags mark every 10 links (or every 5 m/10 m) to make reading easy; used with arrows (pins) and ranging poles to measure distances in chain surveys.
(b) Links bend or stretch, giving wrong lengths; sagging of the chain on uneven ground; obstacles such as rivers, buildings and thick bush on the line; slow and difficult on marshy or broken ground; heavy and tiring to carry; tangling and kinks; errors in counting chains and booking.
Describe its length, links and tags, then the difficulties in the field.