One of the most important advances in medicine occurred in 1796, when Edward Jenner infected a child with cowpox. Jenner demonstrated that the mild cowpox infection protected the child against a similar but much deadlier disease, smallpox. Jenner called his process vaccination, and the substance used was called a vaccine.

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Regeneration–the ability of animals to replace lost body parts–was first studied by scientists in the 18th century. In 1712, Rene’ Antoine Ferchault de Reaumur [French: 1683-1757] presented a beautifully illustrated paper in which he described the ability of crayfish to regenerate missing limbs.

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In 1896, Antoine Henri Becquerel accidentally ruined some photographic film. He had put some samples of uranium compounds on the film while he waited for a sunny day to experiment. When he developed the film, it had turned black. Becquerel recognized that this occured because uranium releases invisible energy, something like X rays, which had been discovered a year before by Wilhelm Konrad Rontgen.

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The invention of the electric telegraph gave birth to the communications industry . Although Samuel B. Morse succeeded in making the invention useful in 1837 , it was not until 1843 that the first telegraph line of consequence was constructed . By 1860 more than 50,000 miles of lines connected people east of the Rockies . The following year , San Francisco was added to the network .

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