Adjustable parabolic curve

A parabola is the commonest curve in constructional engineering and it shows the gradual change in direction along the curve and so it is used when trying to connect parts of a railway, highway or a bridge for example. Prior to computers, engineers and architects used drawing devices to draw accurate parabolas of various proportions such as this one designed and patented by engineer F.W Davey. The flexible steel curve is constrained by an adjustable brass lattice stiffly jointed so that for any particular adjustment the flexible curve retains its shape and can be used as a template for drawing purposes.