Some examples of protractors in the collection

Military operations frequently require surveying and navigational activities. In addition to the tasks described on those pages of this exhibit, early modern military architects used protractors to create designs for fortifications. In the 20th century, protractors were utilized to position artillery pieces. The collections are especially rich in examples from the Felsenthal Instruments Company, a Chicago manufacturer of scientific instruments that was influential from the 1940s to the 1970s.