 These consisted of two strong poles, which were set several meters apart at the base and then lashed together at the top to form a triangle; this was stabilized and kept vertical by guy ropes fixed to the apex, stretched taut and tied to stakes driven into the ground some distance away.Using pulleys and ropes hung from the apex of the shear, the navvies hoisted the columns, girders and other parts into place.As soon as two adjacent columns had been erected, a girder was hoisted into place between them and bolted onto the connectors.