appointed chief engineer of the Edison Lamp Works. In his first year, the plant under general manager Francis Robbins Upton turned out 50,000 lamps. According to Edison, Hammer was "a pioneer of incandescent electric lighting". Frank J. Sprague, a competent mathematician and former naval officer, was recruited by Edward H. Johnson and joined the Edison organization in 1883. One of Sprague's contributions to the Edison Laboratory at Menlo Park was to expand Edison's mathematical methods. Despite the common belief that Edison did not use mathematics, analysis of his notebooks reveal that he was an astute user of mathematical analysis conducted by his assistants such as Francis Robbins Upton, for example, determining the critical parameters of his electric lighting system including lamp resistance by an analysis of Ohm's Law, Joule's Law and economics. Nearly all of Edison's patents were utility patents, which were protected for 17 years and included inventions or processes that are electrical, mechanical, or chemical in nature. About a dozen were design patents, which protect an ornamental design for up to 14 years. As in most patents, the inventions he described were improvements over prior art. The phonograph patent, in contrast, was unprecedented in describing the first device to record and reproduce sounds. In just over a decade, Edison's Menlo Park laboratory had expanded to occupy two city blocks. Edison said he wanted the lab to have "a stock of almost every conceivable material". A newspaper article printed in 1887 reveals the seriousness of his claim, stating the lab contained "eight thousand kinds of chemicals, every kind of screw made, every size of needle, every kind of cord or wire, hair of humans, horses, hogs, cows, rabbits, goats, minx, camels ... silk in every texture, cocoons, various kinds of hoofs, shark's teeth, deer horns, tortoise shell ... cork, resin, varnish and oil, ostrich feathers, a peacock's tail, jet, amber, rubber, all ores ..." and the list goes on. Over his desk Edison displayed a placard with Sir Joshua Reynolds' famous quotation: "There is no expedient to which a man will not resort to avoid the real labor of thinking." This slogan was reputedly posted at several other locations throughout the facility. In Menlo Park, Edison had created the first industrial laboratory concerned with creating knowledge and then controlling its application. Edison's name is registered on 1,093 patents. Phonograph Edison began his career as an inventor in Newark, New