Illustration form De Magnete by William Gilbert, published in 1600. A blacksmith pounding a cooling bar of steel while it is aligned in the north-south (SEPTENTRIO-AUSTER) direction. The bar captures some of the Earth's magnetism. William Gilbert (May 24, 1544 - November 30, 1603) was an English physician, physicist and natural philosopher. He is regarded by some as the father of electrical engineering. His primary scientific work was De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure (On the Magnet and Magnetic Bodies, and on the Great Magnet the Earth) published in 1600. From his experiments he concluded that the Earth was itself magnetic and that this was the reason compasses point north. He was the first to argue that the center of the Earth was iron, and he considered an important and related property of magnets was that they can be cut, each forming a new magnet with north and south poles. He invented the first electrical measuring instrument, the electroscope, in the form of a pivoted needle he called the versorium. He died in 1603 at the age of 59. His cause of death is thought to have been the bubonic plague.