Emily C. Duncan facts for kids

Emily Cornelius Duncan (born in 1849) was an American inventor. She created special calculators for banks and received two patents for her inventions in 1903 and 1904.

Emily was born in 1849 in a place called Coral, Illinois. Later, she lived in Centralia, Wisconsin (which is now Wisconsin Rapids) and Jennings, Louisiana. She became known for her new banking calculators and was even mentioned in a magazine called Inventive Age in February 1905. Emily Duncan was one of many women who were inventing things during a time when technology was growing, even before modern computers existed.

Emily was married to another inventor, James Eugene Duncan. People often thought he was the only inventor in the family. However, her granddaughter later wrote that Emily helped her husband with many of his inventions too!

Inventing for Banks

Emily Duncan had clear goals for her inventions. She wanted to create tools that were "simple and readily understood." This meant they should be easy for anyone to use. Her main aim was to help people do math problems quickly and accurately, especially those that usually took a lot of time and care.

Another goal for her inventions was to make them flexible. She wanted to design devices where parts could be easily changed. This way, the same calculator could be used to solve different kinds of math problems.

The First Calculator

Emily's first calculator was designed to figure out interest. Interest is the extra money you pay when you borrow money, or the extra money you earn when you save money. Her calculator could compute interest at different rates: six, seven, or eight percent.

This calculator was first made so that any mathematician could use it easily. Emily's original patent application included detailed drawings of two different versions of the calculator. These drawings also explained exactly how the calculator was supposed to work. This invention was especially good at doing calculations involving hundreds.

Improving Calculators

In 1904, Emily received another patent for an improved calculator. This new invention was all about making time-calculators better. A time-calculator helps you figure out how many days are between two different dates.

Her goal for this second invention was to make the calculator stronger and more durable. She wanted to create a device that could accurately determine the exact number of days between any two dates within a single year. This was very helpful for banks and businesses that needed to track time precisely.

See also

• In Spanish: Emily C. Duncan para niños