Mathematical Charts and TablesConversion Tables
As has been suggested already, instructive mathematical charts introduced unfamiliar units of measure. A number of handy tables also were produced to assist in conversions. Perhaps the earliest such chart in the collections dates from about 1814, and is designed to convert from units divisible by twelfths to decimal units. The size of conversion factor and the way the numbers are written suggest that it was made to convert from Massachusetts pounds and shillings to U.S. currency. By the mid-20th century, the dollar prevailed throughout the United States, and Americans were more concerned with understanding foreign currencies when they traveled abroad. Toward that end, some purchased a slide chart called the UNICON, which allowed them to convert between dollars and numerous foreign currencies when they knew the exchange rate.
Engineers have long needed to perform conversions as part of their work. In the first half of the 20th century, manufacturers sometimes distributed small advertising cards that listed decimal equivalents of parts of an inch. Larger tables might list a large number of useful conversion factors. New efforts to introduce metric weights and measures in the United States in the 1970s led to the distribution of a range of cards and slide charts that eased conversions. These were distributed by organizations ranging from the federal government to a manufacturer of outdoor clothing and camping supplies to a producer of food emulsifiers and flavorings.
"Mathematical Charts and Tables - Conversion Tables" showing 1 items.
- In the 1970s, after metric units of measure had been adopted in Canada and Great Britain, some people in the United States advocated adoption of the metric system. The National Bureau of Standards of the U. S. Department of Commerce prepared this white plastic reference card to assist those wishing to use the unfamiliar units of measure. One side gave approximate conversion factors for computing metric measures from customary measures of length, area, mass and volume. This side also has a scale eight centimeters long divided to millimeters, and a chart with temperatures in degrees Fahrenheit along the top and temperatures in degrees centigrade along the bottom.
- The other side of the card gives factors for converting from metric to common measures of length, area, mass, volume, and temperature. There also is a scale three inches long divided to 1/16th of an inch.
- The card was a gift of machinist George A. Norton, a longtime employee of the National Museum of American History.
- Currently not on view
- date made
- U.S. Department of Commerce, National Bureau of Standards
- ID Number
- catalog number
- nonaccession number
- Data Source
- National Museum of American History, Kenneth E. Behring Center