At the age of 21, Martha J. Coston found herself widowed and with four children to support. When her husband, a former naval scientist died, Martha found plans for a pyrotechnic (signal) flare in his notebook and decided that she could design a signal flare that would work. She faced two big challenges before she could come up with a design. First, the flares had to be simple enough to use in coded color combinations. Second, they had to be bright, durable, and long-lasting so that they were effective tools for ship-to-ship and ship-to-land communications.
After several years of working on the design, Martha hit on the idea of using fireworks technology as the basis of her design. Once Martha thought of using fireworks technology, she developed the original plan into an elaborate system of flares called Night Signals. She received her patent for her Pyrotechnic Night Signals on April 5, 1859. The U.S. Navy then paid her $20,000 for the patent rights to the flares. They also awarded Martha the contract to manufacture them. Martha's flares served as the basis of a system of communication that helped save lives and win battles during the Civil War. Some historians have said that the signal flares helped the North to win the war.
After the war, Martha continued to improve her invention and came up with a twist-ignition device that she patented in 1871. The Coston Supply Company established by Martha Coston remained in business into the late 1970s. Martha sold her flares to navies, shippers, maritime insurance companies, and yacht clubs around the world like France, Italy, Denmark, the Netherlands, and Haiti. The system of bright, long-lasting signal flares revolutionized naval communication and continues to be in use. Coston's invention saved many lives.The effectiveness of Pyrotechnic Night Signals attracted the U.S. Navy and till now these devices are still used.
Image take from the cover of The Inventions of Martha Coston: Signal Flares That Saved Sailors' Lives.