Large Scale Prototype-protractor De Martin - 1862

Very rare model of Martin's very large "protractor scale" manufactured by Colombi. It is also a copy of a present offered to "Monsieur le Directeur de l'Institut de France" and accompanied by a drawing dated "October 29, 1862". The instrument is kept in its original wooden case. It is approximately 45cm long. This instrument seems to be a presentation prototype and moreover seems to have never been manufactured for mass sale since we do not know of any other specimen and we could not find any information about this instrument in the documentation. old or in the database of French patents from the 19th century. Also, we could not identify "Martin surveyor 1st class" with certainty but we do know that Colombi patented a "method for the choice of spectacles" and tried to develop a new portable barometer in the 1860s. Extremely rare French drawing/engineering/mathematics instrument.