Dividers & CompassesProportional Dividers
Unlike regular dividers, proportional dividers have points at both ends. A screw and nut slide along a slot within the legs to allow the instrument to be opened into an "X" shape. The user then tightens the screw at a particular proportion in order to make scale drawings, such as for engineering or architecture. Proportional dividers are especially helpful when the drafter must change between several different scales. However, for one of these objects, there was only one desirable proportion, the so-called "universal ratio" of 5.333:1. Maurice Kidjel, a Hawaiian artist and inventor, sought out and received publicity for his device in the 1960s.
"Dividers & Compasses - Proportional Dividers" showing 1 items.
- The pointers on this German silver drawing instrument are held in place with screws, meaning that they can be adjusted and replaced. The points are 1-1/8" and 1/2" long. The front slide has scales for lines, running by ones from 1 to 10, and for circles, irregularly numbered from 6 to 36. Thumbscrews on both sides adjust the instrument along a gear and tooth mechanism (or "rack movement") on the back slide. The front slide is marked: TACRO INC. (/) GERMANY. The case is covered with black leather and lined with blue velvet. It is unlocked by pulling out a button on the right side of the case. The case is marked on the top: TACRO. It is also marked: 4130. The case is marked on the bottom: Made in Germany.
- Tacro is a manufacturer of drawing instruments apparently established in the 20th century. According to online auction records, it marked its products as made in West Germany from about 1950 to 1991. Thus, this object probably dates to the 1930s or 1940s. As of 2012, Tacro continues to make these proportional dividers.
- Currently not on view
- date made
- ca 1940
- ID Number
- accession number
- catalog number
- Data Source
- National Museum of American History, Kenneth E. Behring Center