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A jewel bearing is a plain bearing in which a metal spindle turns in a jewel-lined pivot hole. The hole is typically shaped like a torus and is slightly larger than the shaft diameter. The jewels are typically made from the mineral corundum , usually either synthetic sapphire or synthetic ruby .
For watch bearings, a jewel bearing made of ruby, comprising a ring (the "hole") with a sink for oil, is invented by Nicholas Facio with Peter and Jacob Debaufre, who use pierced natural rubies. Other gemstones are used subsequently, including garnet (which is too soft) and diamond ; in the 20th century, synthetic ruby or sapphire becomes ...
Pierced jewel and capstone, used as a low-friction bearing in a mechanical watch. Lubrication is provided by a small drop of oil, kept in place by capillary action. In the 1690s, Fatio discovered a method for piercing a small and well-rounded hole in a ruby, using a diamond drill.
In the three axis tourbillon movement, the 3rd (external) cage has a unique form which provides the possibility of using jewel bearings everywhere, instead of ball-bearings. This is a unique solution at this size and level of complication. [11] There are a few wrist and pocket watches that include the Triple Axis or Tri-Axial Tourbillon ...
Title page of a printed lapidary by Conrad Gessner of 1565. A lapidary is a text in verse or prose, often a whole book, that describes the physical properties and metaphysical virtues of precious and semi-precious stones, that is to say, a work on gemology. [1]
Frontispiece to A mother's offering... by Charlotte Barton, 1841. A Mother's Offering, [12] which predates subsequent Australian literature for the young by a decade, [6] is written in the genre of children's conversation textbooks, a dialogue between mother and children, [13] reflecting the importance of family conversation to education in the home in the nineteenth century, and follows the ...
Frank Raymond "F. R." Leavis CH (/ ˈ l iː v ɪ s / LEE-vis; 14 July 1895 – 14 April 1978) was an English literary critic of the early-to-mid-twentieth century. He taught for much of his career at Downing College, Cambridge, and later at the University of York.
The techniques for producing jewelled bookbinding have evolved over the course of history with the technologies and methods used in creating books. During the 4th century of the Christian era, manuscripts on papyrus or vellum scrolls first became flattened and turned into books with cut pages tied together through holes punched in their margins.