pentagraphs

A form of pentagraph — A device used in surveying composed of four flat, straight brass rules, two of which are long and are connected by a double pivot at the end to create a V shape, and two of which are short and joined by a double pivot to create another V shape pointed away from the first, with the other ends of the short rules connected at the halfway mark of the long rules, so that the entire figure creates a parallelogram.