Having a patent means that only you have the right to make, use or sell a certain object or idea. George Washington signed the first patent law on April 10, 1790. The new law was called the Patent Act. It kept other people from stealing an inventor's ideas.

To receive a patent, an invention must be new. It must do something useful. The invention can also make an already existing invention better. Patents can be given for machines, products and devices. Chemicals, food and drugs can also be patented. Inventors can get patents for the method to make them.

In the past, not everyone could get patents. For example, enslaved African-Americans were seen as property and couldn't get patents. This didn't stop them from making new inventions, though. In 1721, an enslaved person named Onesimus made a treatment for a terrible disease called smallpox. Papan was another enslaved person who lived in the 1700s. He found a new way to treat skin diseases. It worked so well that Virginia lawmakers freed him so that he could work as a doctor and heal people.

Many people who invented new devices were African-American. Some of them were enslaved, others were free. Most of their stories have been forgotten.

Here are the stories of three African-American inventors. They all lived in the 1700s, and they were all born free.

Benjamin Banneker

Benjamin Banneker was born in 1731. He taught himself math and became a mathematician. When he was 21, Banneker saw a pocket watch. It made him extremely curious. He studied watches and then decided to build his own. A year later, Banneker invented a clock made out of wood. It struck a gong every hour and was very precise. Banneker's wooden clock kept time for more than 40 years.

In 1792, Banneker wrote "Banneker's Almanac." Almanacs were books that told exactly when the sun came up in the morning and set at night. Almanacs also had many other useful pieces of information.

Banneker gave one of the first copies to founding father Thomas Jefferson. He asked Jefferson to give black men and women equal rights and to fight against discrimination. But slavery did not end until 59 years after Banneker died.

James Forten

James Forten, who lived from 1766 to 1842, was born in Philadelphia, Pennsylvania. He served in the U.S. Navy during the Revolutionary War against Britain. Americans were ruled by the British at the time. Forten was captured by the British, and they offered him his freedom if he moved to Britain. Forten refused and said he never would become a traitor.

After the war, Forten became a sailmaker. He created a device to handle ship sails. He patented his invention and became rich. Forten used his money to support the movements for women's rights and ending slavery.

George Peake

George Peake was born in 1722 and died in 1827. Peake fought in the Revolutionary War. He was the first African-American in the town that later became Cleveland, Ohio.

Peake invented a hand mill for grinding corn. Peake's invention was easier to use compared to older methods. It also ground the corn more smoothly.