The radius of this circle would be the radius of the big hole minus the radius of the cog, as the pen-hole stays a fixed distance away from the outside edge of the big hole. Or from that set, using one of the shapes that isn’t circular, like the long thin extended one, or the rugby-ball shaped cog. Intuitively, C i {\displaystyle C_{i}} is too large to roll inside the same-sized C o {\displaystyle C_{o}} without slipping. Now define the new (relative) system of coordinates ( X ′ , Y ′ ) {\displaystyle (X',Y')} with its origin at the center of C i {\displaystyle C_{i}} and its axes parallel to X {\displaystyle X} and Y {\displaystyle Y} .

Spirograph Deluxe Set | The Entertainer

While I can’t pinpoint exactly who invented the Spirograph, I found out about spiral drawing devices as the inspiration behind the toy.

As with many inventions, it’s hard to pinpoint who exactly came up with the idea for a Spirograph, but we can look to a few different people as potential inventors.

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Once either of these rings were held in place (either by pins, with an adhesive, or by hand) any of several provided gearwheels (or rotors)—each having holes for a ballpoint pen—could be spun around the ring to draw geometric shapes.In 1827, Greek-born English architect and engineer Peter Hubert Desvignes developed and advertised a "Speiragraph", a device to create elaborate spiral drawings. Hearst UK is the trading name of the National Magazine Company Ltd, 30 Panton Street, Leicester Square, London, SW1Y 4AJ. One way to try to make sense of something complex is to pick a thing to simplify, and see what happens.