The simplest is to use three tape measures to create a grid using the 3,4,5 method. Measuring a position from a grid using this method is called ‘off-setting’. Based on simple geometry, a 90 degree right angle can be created by making the tapes work together as a triangle with sides of exactly 3, 4 and 5 metres. When the long side (the hypotenuse) is 5 (or a multiple of 5 - as in Pythagoras’s theorem), 3 and 4 (or their multiples) should therefore meet at a right angle. Vertical heights, such as slopes, can be measured using tapes and measuring rods in a step-like fashion.

 

Once a survey grid has been created across a site, and its intersections marked with canes or pegs, a detailed plan of the earthworks within the grid can be created using a plane-table. This is a flat drawing board set on a tripod exactly over a known point, to which a measuring tape is attached and extended by one surveyor to each of the points which are to be recorded. A simple instrument like a ruler with a rifle-sight on top called an ‘alidaide’ allows the operator to sight along the tape to a vertical measuring rod at the recording point, and to draw a line at 1:10 or 1: 100 scale on the plan. Finishing the plan is a dot-to-dot and line-to-line illustrative exercise. Occasionally, a ‘self-reducing alidaide’ is used, which can provide vertical as well as horizontal measurements. Regarded by some people as old-fashioned and out-moded by Total Stations, but still much-valued by their admirers, these are now not easy to get hold of.