Kaleidoscope Wheels: How Rotating Wheels Change the Image

3 days ago

7 min read

Updated: 2 days ago

By Rocco (Roi) Ramon - licensed architect, founder of Studio Yabaye

https://www.youtube.com/watch?v=1OCdBc5pfsQ

A kaleidoscope with wheels keeps its objects outside the tube. One or more discs sit on an axle in front of the mirror system, and the viewer turns them by hand. The mirrors do the same work as in any other kaleidoscope: they repeat whatever is in front of their open end. The wheel decides what that is, and the hand decides when and how fast it changes.

In this article I explain what an object wheel is, how it differs from a closed object cell, what a second and a third wheel add, and how I turn the wheels when viewing. For the mirror side of the instrument, see how a kaleidoscope works.

What an object wheel is

An object wheel is a disc that carries coloured elements fixed in place. It is mounted on an axle at the far end of the tube. In my instruments the axle is mounted directly beside the mirror system, to one side of the optical axis, so the mirror opening looks through a zone of the disc between the hub and the rim. When the wheel turns, that zone travels across the opening along an arc.

In my studio, every object wheel is cast in crystal-clear resin, holding coloured elements, and is poured and composed by hand. The elements include beads, glass stones, sequins, glitter, liquid and powder pigments, threads and shavings. They also include opaque pieces such as stones, simple gemstones, shells, charms and brass rings in several sizes, and leaves, plants and dried flowers. Because the composition is done by hand, no two pieces are alike.

Object wheel vs closed object cell

A closed object cell is a container at the end of the tube that holds loose pieces, dry or in liquid. I covered it in what goes in a kaleidoscope object cell and in oil-filled vs dry cell. The difference from a wheel is mechanical.

Source of motion. In a dry cell the pieces fall under gravity when the cell is turned. In an oil-filled cell they drift in the liquid. In a wheel, the only motion is the rotation applied by hand.
Repeatability. Loose pieces rarely return to the same arrangement. A wheel with fixed elements shows the same arrangement each time it returns to the same angle. In my wheels everything is fixed: only the wheels themselves rotate.
Control. A wheel can be turned forward or backward at any speed, so a pattern that has passed can be brought back.

Brewster identified the limit of loose objects in his "Treatise on the Kaleidoscope" (Edinburgh, 1819). In Chapter VI he writes that because the fragments always descend by their own gravity, the changes in the picture "constantly take place in a similar manner". In Chapter VII he describes an alternative supplied with the instrument: an object plate with pieces of glass fixed by a transparent cement, so that the patterns "may be exhibited to others". After a complete rotation, he writes, "the same patterns again recur". Those two chapters do not describe a wheel on an external axle, but in function a fixed-element wheel belongs to the second type.

One wheel, two wheels, three wheels

One wheel. The image is a sequence that repeats once per revolution. Every small angle gives a different crop of the disc, but the sequence is closed.

Two wheels. Two discs sit one behind the other on a common axle and can be turned together or separately. The mirror opening now looks through two layers at once. Three effects appear that a single wheel cannot give:

Colour mixing by overlap. Where a transparent element of one wheel covers a transparent element of the other, the light passes through both. Each layer absorbs part of the spectrum, so the overlap shows only what both layers transmit. This is subtractive mixing: a yellow layer over a cyan layer reads as green, and every overlap is darker than either layer alone. The exact result depends on the glass and pigments in each element.
Relative motion. When one wheel is held and the other is turned, part of the pattern stays fixed and part moves across it.
Combination count. The image depends on two independent angles. After one revolution of one wheel, the pattern returns only if the other wheel is where it was before.

Counter-rotation. When the two wheels are turned in opposite directions, the elements of one layer cross the opening one way while the elements of the other cross it the opposite way. The overlap colours appear and disappear as the elements pass each other. This is how I turn the wheels: at the same time, in opposite directions.

Three wheels. A third layer adds a third independent angle and a third filter in the light path. Overlaps of three transparent elements are possible, and they transmit less light than overlaps of two, because each layer absorbs part of it.

I build two-wheel and three-wheel models. The mirror systems behind the wheels include two-mirror and three-mirror configurations, with front-surface mirrors cut to size for each model. For the difference in the image between mirror systems, see two-mirror vs three-mirror kaleidoscopes, and for the geometry behind it, mirror angle and number of points.

Transparency, colour density and strong light

A wheel is viewed by transmitted light. The light source is behind the wheel, and what reaches the eye is what the wheel lets through.

Transparent elements show their colour and remain readable when layers overlap.
Dense or dark elements transmit little light, and need a strong source to show colour.
Opaque elements block the light and read as outlines.
Clear areas pass the light almost unchanged and set the brightest value in the image.

Brewster's instruction for transparent objects, in Chapter VII of the 1819 treatise, is to reject fragments of opaque glass and "dark colours that do not transmit much light".

The practical consequence concerns the light source. A kaleidoscope needs direct light, preferably strong, and not side light. With stacked wheels this matters more, because every added layer subtracts light. In weak light, the overlaps read as dark areas and the image shows fewer colours than the wheels contain.

How to turn the wheels when viewing

Aim first. Point the far end of the tube at a direct, strong light source, such as a bright window or open sky. Never point any optical instrument at the sun.
Use two hands. One hand holds the tube and the other turns the wheels. One-handed use is possible, but I recommend it less.
Start with one wheel. The wheels sit on a common axle and can be turned together or separately. Turn one wheel slowly through a full revolution and leave the others at rest. This shows what that wheel contains.
Counter-rotate. Turn the wheels at the same time in opposite directions. Watch the overlap colours form and break.

The studio site has several videos showing the interior view.

Checklist: reading a wheel kaleidoscope

Can the wheels be turned together and separately?
Are enough elements transparent to show colour in transmitted light?
With two wheels, do the overlaps produce a visible third colour?
In direct strong light, are the overlap areas still readable?
Can a pattern be brought back by reversing the wheel?

FAQ

What is a wheel kaleidoscope?

A wheel kaleidoscope carries its objects on one or more discs mounted on an axle in front of the mirror system. The viewer turns the discs by hand. The coloured elements are fixed in each disc, so they do not fall or drift, and the image changes only while a wheel is being turned.

How is an object wheel different from an object cell?

An object cell is a closed container with loose pieces that fall under gravity or drift in liquid, so an arrangement rarely returns. An object wheel holds fixed elements in a disc. It can be turned forward or backward at any speed, and each angle of the wheel shows the same arrangement again.

What does a second wheel add to a kaleidoscope?

A second wheel puts two layers in front of the mirrors. Where two transparent elements overlap, the light passes through both and a third colour appears, such as green from yellow over cyan. The image depends on two independent angles, so one layer can stay fixed while the other moves across it.

Does a kaleidoscope with wheels need strong light?

Yes. The wheels are viewed by transmitted light, and each layer absorbs part of it. A kaleidoscope needs direct, preferably strong light, not side light. In weak light, the areas where two or three layers overlap read as dark shapes and the image shows fewer colours than the wheels contain.

Do wheel kaleidoscope patterns repeat?

With one wheel of fixed elements, the same pattern returns at the same angle once per revolution, a property Brewster described for fixed objects in 1819. With two or three wheels, the image depends on the angle of every wheel together, so an exact repeat requires all of them to return to the same positions.

Are two object wheels ever identical?

Not in my studio. Every Studio Yabaye object wheel is cast in crystal-clear resin, holding coloured elements such as beads, glass stones, shells, brass rings and dried flowers, and is poured and composed by hand. The position, size and colour of the elements differ from wheel to wheel, so no two pieces are alike.

About Studio Yabaye

Studio Yabaye builds kaleidoscopes and teleidoscopes with front-surface mirror systems in several configurations, in a brass tube, cut, fitted and hand-finished in the studio. Each object wheel is poured and composed by hand, so no two pieces are alike. The range includes two-wheel and three-wheel models. The studio is based in Israel and ships worldwide. The current range is at all products, and questions can be sent through the contact page.