Galileo became so associated with the sector that many people incorrectly believed he was the instrument's only inventor. Even though the collection is small, the Museum's holdings suggest there was little consensus in seventeenth-century Italy about which arrangement of scales was most essential to mathematical practitioners' activities. Indeed, Galileo himself experimented with several different scales during the decade he spent working on the instrument before he formally published Operations of the Geometric and Military Compass. One reason for the variety is he started out thinking only about military applications but gradually decided to develop a general-purpose device. The Italian sectors in the collection might have been used for tasks ranging from positioning a cannon and designing fortifications to converting between systems of currency.
"Sectors - Italian Style" showing 1 items.
- The two arms on this brass hinged sector have decorative curves at one end. An acanthus scroll motif is on the hinge. Five double scales (i.e., the scales on one arm are identical to those on the other arm) are on one side. The scales are labeled on both legs. The outermost scale is labeled Metallorum and marked with the letters: Aur, Mer, Plu, Arg, Cup, Fer, Sta, Mar, Sax. These correspond to the specific weights of different metals. The second scale runs from 4 to 40 and is labeled Quadratrix Segmentorum. The third scale is marked with engravings of various polyhedra and the letters: D, I, C, S, O, T. It is labeled Solidorum Regularum. The fourth scale runs from 20 to 3. The letters D and R are on either side of the number 7. The scale is labeled Planorum AEqualium. The innermost scale runs from 10 to 180 and is labeled Graduum Circuli.
- The reverse side has four double scales. The outermost runs from 20 to 3 and is labeled Figurarum Regularium. The second runs from 1 to 100 and is labeled Planorum. The third runs from 1 to 125 and is labeled Solidorum. The innermost scale runs from 20 to 300 and is labeled Partium AEqualium. One arm has a scaled diagram, labeled Orthographia Munimentorum, for dividing various heights, lengths, and depths of military fortifications into sections. The other arm has a table labeled Tabula Ignographia Munimentorum that gives the proportional dimensions for areas of fortifications that have between four and ten sides.
- The outer edges of the arms have scales that run from 1/4 to 64. One is labeled Poids des boulets, and the other is labeled Calibre des pieces. Although most of the scales on this instrument reflect the Italian style of sector, these scales are typical of sectors made for the French market. See, for example, MA*321676 and MA*333929.
- In the closed position, the front of the sector reads: Iacobus Lusuerg (/) Mutinensis Faciebat (/) Roma Ao. 1683. Jacob Lusuerg and his son, Dominicus, made mathematical instruments in Rome and Modena from 1674 until 1719. Henry Russell Wray, the previous owner of this instrument, graduated from the University of Pennsylvania and was a businessman in Colorado Springs, Colo., in the early 20th century.
- References: Jim Bennett and Stephen Johnston, The Geometry of War, 1500–1750 (Oxford: Museum of the History of Science, 1996); Maya Hambly, Drawing Instruments, 1580–1980 (London: Sotheby's Publications, 1988), 25.
- Currently not on view
- Currently not on view
- date made
- Lusuerg, Jacobus
- ID Number
- accession number
- catalog number
- Data Source
- National Museum of American History, Kenneth E. Behring Center