Post by Admin on Aug 5, 2021 17:30:10 GMT
The Spiralist
By Dr Kevin Dann
Why do helical seashells resemble spiraling galaxies and the human heart? Kevin Dann leads us into the gyre of James Bell Pettigrew’s Design in Nature (1908), a provocative and forgotten exploration of the world’s archetypal whorl.
PUBLISHED
August 5, 2021
publicdomainreview.org/essay/the-spiralist
One halcyon spring day in 1903, the sixty-nine-year-old anatomist and naturalist Dr. James Bell Pettigrew sat at the top of a sloping street on the outskirts of St. Andrews, Scotland, perched inside a petrol-powered aëroplane of his own design. Over the course of forty years, ever since he began his aeronautical experiments in London in 1864, Pettigrew had constructed dozens of working models of various flying apparatus. From anatomical dissection and observations of animals in the wild and at the London Zoo, Pettigrew had come to conceive of all creatures — whether on land, in water, or in the air — as propelling themselves by throwing their bodies into spiraling curves, such that their movements were akin to waves in fluid, or to waves of sound. Instead of driving the wings vertically as in other flying machines modeled on animal flight, Pettigrew’s “ornithopter” emulated the movement that he had discovered to be universal in flying creatures: rhythmic figure-of-eight curves. To permit this undulatory motion, Pettigrew had furnished the root of the wing with a ball-and-socket joint; to regulate the several movements of the vibratory wing — comprised of bamboo cane from which issued tapering rods of whalebone covered in a thin sheet of India rubber — he employed a cross-system of elastic bands. A two-stroke engine’s piston drove this elaborate apparatus of helical biological mimicry.
By Dr Kevin Dann
Why do helical seashells resemble spiraling galaxies and the human heart? Kevin Dann leads us into the gyre of James Bell Pettigrew’s Design in Nature (1908), a provocative and forgotten exploration of the world’s archetypal whorl.
PUBLISHED
August 5, 2021
publicdomainreview.org/essay/the-spiralist
One halcyon spring day in 1903, the sixty-nine-year-old anatomist and naturalist Dr. James Bell Pettigrew sat at the top of a sloping street on the outskirts of St. Andrews, Scotland, perched inside a petrol-powered aëroplane of his own design. Over the course of forty years, ever since he began his aeronautical experiments in London in 1864, Pettigrew had constructed dozens of working models of various flying apparatus. From anatomical dissection and observations of animals in the wild and at the London Zoo, Pettigrew had come to conceive of all creatures — whether on land, in water, or in the air — as propelling themselves by throwing their bodies into spiraling curves, such that their movements were akin to waves in fluid, or to waves of sound. Instead of driving the wings vertically as in other flying machines modeled on animal flight, Pettigrew’s “ornithopter” emulated the movement that he had discovered to be universal in flying creatures: rhythmic figure-of-eight curves. To permit this undulatory motion, Pettigrew had furnished the root of the wing with a ball-and-socket joint; to regulate the several movements of the vibratory wing — comprised of bamboo cane from which issued tapering rods of whalebone covered in a thin sheet of India rubber — he employed a cross-system of elastic bands. A two-stroke engine’s piston drove this elaborate apparatus of helical biological mimicry.