Watch Jewels
Jewel bearings were invented and introduced in watches by Nicolas Fatio (or Facio) de Duillier and Pierre and Jacob Debaufre around 1702 to reduce friction. They did not become widely used until the mid 19th century. Until the 20th century they were ground from tiny pieces of natural gems. Watches often had garnet, quartz, or even glass jewels; only top quality watches used sapphire, ruby, or diamond. In 1902, a process to grow artificial sapphire crystals was invented, making jewels much cheaper. Jewels in modern watches are all synthetic sapphire or (usually) ruby, made of corundum (Al2O3), one of the hardest substances known. The only difference between sapphire and ruby is that different impurities have been added to change the color; there is no difference in their properties as a bearing. The advantage of using jewels is that their ultrahard slick surface has a lower coefficient of friction with metal. The static coefficient of friction of steel-on-steel is 0.58, while that of sapphire-on-steel is 0.10-0.15.
Read more about this topic: Mechanical Watch
Famous quotes containing the words watch and/or jewels:
“It is dangerous to leave written that which is badly written. A chance word, upon paper, may destroy the world. Watch carefully and erase, while the power is still yours, I say to myself, for all that is put down, once it escapes, may rot its way into a thousand minds, the corn become a black smut, and all libraries, of necessity, be burned to the ground as a consequence. Only one answer: write carelessly so that nothing that is not green will survive.”
—William Carlos Williams (1883–1963)
“Women hock their jewels and their husbands’ insurance policies to acquire an unaccustomed shade in hair or crêpe de chine. Why then is it that when anyone commits anything novel in the arts he should be always greeted by this same peevish howl of pain and surprise? One is led to suspect that the interest people show in these much talked of commodities, painting, music, and writing, cannot be very deep or very genuine when they so wince under an unexpected impact.”
—John Dos Passos (1896–1970)