**Lemniscate** The word lemniscate comes from the Greek word *lemniskus* for ribbon. The mathematical curve, a sort of figure eight, does look somewhat like the bow for a package made from a twisted ribbon [see figure]. The word is beginning to disappear from textbooks, and is completely missing in my high school edition of the American Heritage Dictionary. The only closely related term I could find was lemniscus, a term for a nerve bundle in the brain. No picture was available, but it may be this also looks like a ribbon.

The Mathematical curve [formulas below]is related to the rectangular hyperbola through the following relationship. If a tangent is drawn to the hyperbola and the perpendicular to the tangent is drawn through the origin, the point where the perpendicular meets the tangent is on the lemniscate.

I recently saw a picture of a chemical periodic table in the shape of a lemniscate created by William Crookes in 1888. The picture is on page 107 of The Ingredients: A Guided Tour of the Elements by Philip Ball.

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