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In box that I would think is original, it has paper tape stuck all around the edges so cannot see if the box has any markings, the mathematical tool measures 27” in length when closed up straight. The only other one we know of is at the London’s Science museum. Dates 1924-1925
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.
Price is inclusive of postage to mainland U.K.
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