Читать книгу Magic Shadows. The Story of the Origin of Motion Pictures онлайн

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Alhazen went to Egypt and made preliminary calculations. He saw that the task was impossible with available tools, men and knowledge, but to admit failure in those days usually meant losing a life—one’s own. Absolute rulers did not like to have agreements broken. Alhazen feigned madness and escaped. By pretending to lose his head he saved his life.

Despite his failure with the Nile, Alhazen is regarded as the first great discoverer in optics after the time of Ptolemy. The Arabs were enthusiastic followers of Aristotle and also knew of the work of Archimedes, Ptolemy and other Greek scholars.

Alhazen’s great work, Opticae Thesaurus Alhazeni Arabis, was first printed in 1572 but manuscript copies of the De Aspectibus or Perspectiva and the De Crepusculis & Nubium Ascensionibus had found their way about the late 12th century into all the great libraries of the Middle Ages and his influence on all subsequent work in optics was great and widespread. The book is very curious, covering a multitude of subjects. Alhazen studied images, the various kinds of shadows and even attempted to calculate the size of the earth. He is credited with being the first to explain successfully the apparent increase of heavenly bodies near the horizon—the familiar phenomenon of the great sun at sunset and the huge harvest moon as it comes up in the East. Light also was extensively considered by Alhazen and he treated its use, setting down many rules on reflection and refraction. He recognized the element of time necessary to complete the act of vision; in other words, the persistence of vision or the time lag. He gave a description of the lens’ magnifying power as he was familiar with various lenses and mirrors.