Cenco Gas Volume Reduction Circular Slide Rule

This yellow paper circular rule consists of two discs, one with a protruding tab for rotating the disc, held together with a metal grommet. The device reduces the observed volume of a gas to the corresponding volume under standard conditions (0°C, 760 mm pressure). Scales for temperatures from 10 degrees to 35 degrees centigrade and for pressures from 700 to 790 mm run along the lower edge of the rule. Setting the device for an observed temperature and pressure reveals a volume factor and the logarithm of the volume factor in the lower interior of the instrument. The factor is multiplied by the observed volume on the scale along the upper edge of the instrument to arrive at the reduced volume.
The instrument is marked: CentralScientificCo. (/) CENCO (/) CHICAGO U.S.A. (/) GAS VOLUME REDUCTION CHART. It is also marked: Copyrighted 1921, by Central Scientific Co. An advertisement for the "new rotary CENCO hyvac pump," available from Central Scientific's Bulletin No. 92, appears on the back of the device. For another instrument made by Central Scientific Co., see 1982.0147.02.
The front of the instrument indicates that Prof. E. M. Jones of Adrian College in Adrian, Mich., proposed its design. Jones also wrote "Laboratory Versus Recitation," School Science and Mathematics 8 (1923): 749–759. In 1920, he was appointed to the city of Adrian's first water board.
Reference: "Adrian H2O: Over One Hundred Years," http://www.ci.adrian.mi.us/Services/Utilities/History.aspx.
Currently not on view
Object Name
calculating rule
slide rule
date made
after 1921
Central Scientific Company
Physical Description
metal (part material)
paper (overall material)
overall: 13.2 cm x 13.2 cm x .2 cm; 5 3/16 in x 5 3/16 in x 3/32 in
place made
United States: Illinois, Chicago
ID Number
nonaccession number
catalog number
Rule, Calculating
Science & Mathematics
Slide Rules
See more items in
Medicine and Science: Mathematics
Slide Rules
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Oscar W. Richards
Additional Media

Visitor Comments

Add a comment about this object

**Please read before submitting the form**

Have a comment or question about this object to share with the community? Please use the form below. Selected comments will appear on this page and may receive a museum response (but we can't promise). Please note that we generally cannot answer questions about the history, rarity, or value of your personal artifacts.

Have a question about anything else, or would you prefer a personal response? Please visit our FAQ or contact page.

Personal information will not be shared or result in unsolicited e-mail. See our privacy policy.

Enter the characters shown in the image.