Edison inadvertently invented the device that would become the modern tattooing machine. In 1875 he invented an electric writing instrument consisting of a steel needle driven up and down the barrel of a pen. The device punched tiny holes into a stencil that could be used to print many copies of the same document. He received the patent for his Autographic Printing Pen on August 8 1876, but the device was cumbersome and not popular. Improvements were made to the invention in 1877 and sales somewhat improved. In 1891, Samuel O’Reilly modified Edison’s pen idea by introducing an ink filled needle to create an electric tattooing pen. Many improvements were made to the tattoo machine over the years, mostly with the intent to make the machine lighter and allow for better effects, such as shading, by being able to adjust the depth, power and speed of the needle.