Exam Review: Ancient Rome and the Scientific Revolution |
You don't expect to find major advances in the design of telescopes in a book on music. In 1636, Father Marin Mersenne published Harmonie Universelle, a mathematical study of music. It also proposed configurations of mirrors that could be used to produce either telescopic effects or burning mirrors. These configurations were prototypical forms of the Gregorian and Cassegrain telescopes.
There is a side story to Mersenne's and Cavalieri's works. Harmonie Universelle was a book about music but it is important to the history of telescopes. Lo Specchio was a book about mirrors and telescopes but is probably more important to the history of classical mechanics. Lo Specchio contained the first published description of the parabolic nature of projectile motion. Cavalieri's publication of this important concept even caused a short-lived rift in his friendship with Galileo Galilei. Both Galileo Galilei and Thomas Harriot had described projectile motion in private notes but had never published. Mersenne's work on reflecting telescopes was very advanced. Today it is doubted that either he or any of his contemporaries (including Descartes and Galileo) understood the full significance of his work. A full understanding of the advanced nature of Mersenne's work would have to wait until the twentieth century. An indication of this is that the Mersenne telescope, still being produced today, is largely a development of the twentieth century. Mersenne, went further than simply presenting configurations that are used in modern telescopes; his designs featured the strong telephoto effect critical to modern photographic lenses. This all happened 30 years before Newton's telescope [_4_] . Mersenne actually never did build telescopes to his designs. Oddly, he was dissuaded from building them by Rene Descartes. Descartes felt that reflecting telescopes were impractical. Given the technology of the day, he was correct. It would be more than a century before reflecting telescopes were competitive with refractors. The mirrors of the time were made of polished metal which tended to tarnish. Also the tolerances for mirrors is four times more critical than for lenses [_5_] . Why are Mersenne's contributions ignored? It is difficult to find his name in popular histories of the telescope. Mersenne was widely considered to be the inventor of the reflecting telescope in the nineteenth century. Several nineteenth century encyclopedias, including the Encyclopedia Americana , identified Mersenne as the inventor of the reflecting telescope. Others, if they did not credit him with the invention of the reflecting telescope, did mention his contribution to its early development ( see Google Books). Mersenne fell from grace in the twentieth century. Mersenne was not even mentioned in a 1943 survey of the early development of the telescope by the historical journal, Isis [_6_] . The importance given to a historical figure sometimes depends as much on the dominant biases of the day as on their contributions (see Sarton-A Case for Bias).
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