people-from-basel

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April 10, 2026

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"The name is due to Jacques Bernoulli. The spiral has been called also the geometrical spiral, and the proportional spiral, but more commonly, because of the property observed by Descartes, the equiangular spiral. Bernoulli (and Collins at an earlier date) noted the analogous generation of the spiral and loxodrome ("loxodromica"), the spherical curve which cuts all meridians under a constant angle. ... During 1691-93 Jacques Bernoulli gave the following theorems among others: (a) Logarithmic spirals defined [by the polar equation \rho = ke^{c\theta} of a curve cutting radial vectors (drawn from a certain fixed point 0) under a constant angle \phi , where k is constant and c = cot\phi] for different values of k are equal and have the same asymptotic point; (b) the evolute of a logarithmic spiral is another equal logarithmic spiral having the same asymptotic point; (c) the pedal of a logarithmic spiral with respect to its pole is an equal logarithmic spiral (d) the caustics by reflection and refraction of a logarithmic spiral for rays emanating from the pole as a luminous point are equal logarithmic spirals. The discovery of such "perpetual renascence" of the spiral delighted Bernoulli. "Warmed with the enthusiasm of genius he desired, in imitation of Archimedes, to have the logarithmic spiral engraved on his tomb, and directed, in allusion to the sublime tenet of the resurrection of the body, this emphatic inscription to be affixed—Eadem mutata resurgo." The engraved spiral (very inaccurately executed) and inscription in accordance with Bernoulli's desire, may be seen to-day on his tomb in the cloister of the cathedral at Basel."

- Jacob Bernoulli

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