### Related Object Info

### Olivier geometric string figure of two intersecting cylinders

The model sits in a square mahogany box. Each of the four bottom corners is raised on a small round stand. There is a base board trim around the bottom of the box and the top panel extends slightly forming a lip around the top of the box. There is a brass plaque in the center of one edge on the top panel. Henceforth the edge on which the plaque is centered will be used as the 'front' of the box, e.g. the 'right side' of the box is on the right of someone facing center.

The model consists of two differently sized, intersecting cylinders. Each cylinder is 'on its side', meaning that the planes circumscribed by the circles at each end of each cylinder are perpendicular to the top panel of the box. Each cylinder is fixed in a brass frame. Each frame consists, in part, of two parallel thin, horizontal brass bars that run from end to end of the cylinder. The parallel bars are attached by a small brass bar at each end. From each such connecting bar, a small, rectangular sheet of brass with a width the length of the bar rises and attaches to the brass circumference of the circle at that end of the cylinder.

In each frame, a thin brass strip whose flat side is perpendicular to the plane of the brass sheet also rises from the small brass connecting bar. However, instead of ceasing at the edge of the circle, this sheet extends to the top of the circle; the topmost subsection of this strip of brass is the fixed vertical diameter of the circle. There is a similar strip of brass fixed across the horizontal diameter of the each circle.

The two sets of horizontal, parallel bars -- one to support each cylinder -- are each attached to a solid, cylindrical pivot fixed at the center of the top panel of the mahogany box. The parallel bars supporting the larger cylinder are closest to the bottom of the box and the parallel bars supporting the smaller cylinder are at the top of the pivot. The top edge of the smaller cylinder is flush with the top edge of the larger cylinder. As such it is held higher off of the box than the larger one. This is in part the case because the rectangular sheet of metal that rises at each end of the frame to support the smaller circles is longer (approximately double) than the height of those supporting the larger circles.

The circumference of each large circle has 120 equidistant holes around it. There are 60 long, golden strings, folded in half such that each end goes through one of two neighboring holes. Each end goes through two neighboring holes on the circumference of the circle at the other end. The strings are pulled taut between the two circles so that each string represents a ruled edge of the cylinder.

The circumference of each small circle is similarly divided with equally spaced holes and its strings are folded and pulled taut between them.

Crucially, the two sets of taut strings (one set for each cylinder) are intersecting: the strings of the smaller cylinder pass through the strings of the larger cylinder. At each point of intersection -- when one of the strings from the smaller cylinder crosses a string from the larger cylinder -- a small black ring is looped around both strings. That is to say that each point at which a ruled edge of each cylinder crosses the point is marked. The result is that the black markers provide a visual pattern of the intersection of the two spheres. The two cylinders can rotate relative to one another, such that the angle between their horizontal axes (i.e. the axes running through the center of the circular ends) changes. As they rotate, the shape of their intersecting ruled edges changes.