Specially designed hearing aids were described as early as 1588 by Giovanni Battista Porta (1535–1615) in his book NaturalMagick. These hearing aids were made out of wood in the shape of the ears of animals with a sharp sense of hearing. During the 1700s, speaking tubes and ear trumpets were developed. Bone conduction devices to transmit sound vibrations from outside to the bones of the ear, first suggested in 1550 by Gerolamo Cardano (1501–1576), were further developed during the 1800s. The first battery-powered hearing aid in the United States was made by the Dictagraph Company in 1898. Miller Reese Hutchison (1876–1944) filed the patent for the first electric hearing aid in 1901. Refinements were made to the hearing aids throughout the twentieth and twenty-first centuries. Miniaturization and microchips made it possible for hearing aids to become so small they now fit invisibly inside the ear.