Whole Circle Or Dutch Circle Signed Gourdin In Paris C.1770

Beautiful entire circle or Dutch geometry circle Pierre Gourdin active in 1771 and successor of Jean Baptiste Nicolas Bion, son of the famous manufacturer of scientific instruments Nicolas Bion Address: 'Au Quart de Cercle', Quai de l'Horloge 32. The entire circle was first described by Gemma Frisius (1508-1555) in 1533 in her work Libellus de locorum describendorum ratione. Equipped with a compass, this instrument would later be called a “Dutch circle” by mistake by Colonel Laussedat who described Gemma Frisius (1508-1555) to the Dutch. The entire circle, also called a standing circle or sometimes cosmolabe, is made up of a graduated circular plane divided into 360 degrees, composed of four pinnules and mounted on a ball jointed base with butterfly screws. It allows you to measure the angle formed between two distant points by plotting them, which allows you to calculate the distance between them. Its operating principle, based on punctuality, allows use both terrestrial (geodesic or surveying by triangulation) and celestial (calculation of the position of the stars). This instrument, in its shape and functioning, is similar to the astrolabe from which it derives. Many instruments made by Gourdin are today preserved in private collections and museums, testifying to their historical and scientific importance.