Our very own Ian Robinson from the Operations team here at OS took to the fields of France in October to film with BBC’s Countryfile which was aired on BBC1 on Sunday, 9 November. To mark the centenary of World War One we delved into what life would have been like for surveyors on the western front.
Filmed in the village of Sauchy-Lestreé, Ian took us through the old equipment that was used to map the battlefield, and the challenges surveyors faced during this dangerous time. Ian, who has lots of experience working as a Surveyor both at OS and working for the Army for eight years as an Artillery Surveyor, shared with us the intricacies of the job.
The surveying equipment
The surveying equipment used in WW1 is far from the cutting-edge digital products we use today. Here's an insight into some of the equipment featured on the programme:
The theodolite is a precision instrument used for measuring horizontal and vertical angles. It consists of a telescope mounted on a horizontal and vertical axes and is controlled by using coarse and fine adjust screws. When pointed at a target, the angles of these axes can be read from the horizontal and vertical scales.
Ian using old surveying equipment
The tripod is set up over a known point using a plumb bob and the theodolite is attached and levelled using footscrews. The observer sights the telescope on the other survey stations/points of detail, and reads out angles off the scales to a booker, responsible for recording the readings.
The plane table is a wooden board. It’s mounted onto a tripod on which the map or plan is fixed. The plane table is set up over a known point and oriented to another known point by using a sighting device called an alidade. Sightings are taken through the alidade to points of detail and lines or rays, drawn on the plan.
Once drawn, the table is then set up over another known point, orientated by observing back to the first one, then sightings and lines are drawn to the same points of detail. Where the lines intersect is the position of the detail.