1845 edition of the Encyclopedia Metropolitana, posed two ideas for the visual correction: the first "a spherical capsule of glass filled with animal jelly", the second "a mould of the cornea" that could be impressed on "some sort of transparent medium". Though Herschel reportedly never tested these ideas, they were later advanced by independent inventors, including Hungarian physician Joseph Dallos, who perfected a method of making molds from living eyes. This enabled the manufacture of lenses that, for the first time, conformed to the actual shape of the eye. Although Louis J. Girard invented a scleral contact lens in 1887, it was German ophthalmologist Adolf Gaston Eugen Fick who in 1888 fabricated the first successful afocal scleral contact lens. Approximately in diameter, the heavy blown-glass shells rested on the less sensitive rim of tissue surrounding the cornea and floated on a dextrose solution. He experimented with fitting the lenses initially on rabbits, then on himself, and lastly on a small group of volunteers, publishing his work, "Contactbrille", in the March 1888 edition of Archiv für Augenheilkunde. Large and unwieldy, Fick's lens could be worn only for a couple of hours at a time. August Müller of Kiel, Germany, corrected his own severe myopia with a more convenient blown-glass scleral contact lens of his own manufacture in 1888. The development of polymethyl methacrylate (PMMA) in the 1930s paved the way for the manufacture of plastic scleral lenses. In 1936, optometrist William Feinbloom introduced a hybrid lens composed of glass and plastic, and in 1937 it was reported that some 3,000 Americans were already wearing contact lenses. In 1939, Hungarian ophthalmologist Dr.István Györffy produced the first fully plastic contact lens. The following year, German optometrist Heinrich Wöhlk produced his own version of plastic lenses based on experiments performed during the 1930s. Corneal and rigid lenses (1949–1960s) In 1949, the first "corneal" lenses were developed. These were much smaller than the original scleral lenses, as they sat only on the cornea rather than across all of the visible ocular surface, and could be worn up to 16 hours a day. PMMA corneal lenses became the first contact lenses to have mass appeal through the 1960s, as lens designs became more sophisticated with improving manufacturing technology. On October 18, 1964, in a television studio in Washington, D.C., Lyndon Baines Johnson became the first President in the history of the United States to appear in