Option 39: pre-cinema, the start of family H. Three optical toys from the 1820s–1830s, each with the bot drawn in Victorian hand-coloured style:

**Thaumatrope:**
a two-sided spinning card.

**Phenakistoscope:**
a slotted spinning disc.

**Zoetrope:**
a drum viewed through slits.

A "persistence of vision" setting imitates how your eye blends what it glimpses.

**Twelve hand-drawn frames.**
One hop cycle in Victorian lithograph style: ink outlines, hatched shading, a hatched shadow, red motion ticks at the top of the jump and a blink at the apex. All three toys use the same 12 drawings.

**Three devices:**
**Persistence of vision is imitated by blending.**
Each new frame is mixed into the previous image instead of replacing it, roughly how the eye holds what it just saw.

**Phenakistoscope, untick "Look through slits."**
You get a blur and no animation. Slits are what turn spinning into motion: they chop continuous movement into separate glimpses, like a film shutter.

**Slits to 13, then 11.**
With one extra slit the figures creep backwards round the disc; with one fewer, forwards. Real Victorian discs used this deliberately to make parades march.

**Zoetrope, untick "Look through slits" (cut-away).**
The strip just rotates. Tick it again and the slits reveal hopping figures.

**Thaumatrope, untick "Persistence of vision."**
You see the card flicking between a blank-faced bot and floating eyes. Tick it and they fuse into one face.

**Change speed in each mode.**
Too slow and the illusion falls apart; the eye needs enough glimpses per second.

**The back of the thaumatrope is drawn upside down.**
The card flips top to bottom when twirled, so the rear image must be inverted to appear upright.

**The phenakistoscope was viewed in a mirror.**
You held the disc facing a mirror and looked through the slits at the reflection. The simulation shows the resulting view directly.

**These toys are the direct ancestors of film.**
The slit is the shutter, the frame strip is the film, the spin is the projector's advance.

**"Persistence of vision" is a simplification.**
Modern research says motion perception comes from the brain's motion-detecting systems (the "beta movement" and "phi phenomenon"), not just images lingering on the retina. The toys work either way.

**Why slits create animation (phenakistoscope)**
```
disc angle over time: ─────────────────────────────► slit passes eye: | | | | (12 per turn) you glimpse: frame 1 frame 2 frame 3 … at the same spot brain: → one figure hopping in place
```

**Slit count drift**
```
slits = frames (12): each glimpse → figures exactly one step on → hop in place slits = 13: glimpse lands slightly short → figures drift backwards slits = 11: glimpse lands slightly long → figures drift forwards
```

**Thaumatrope card**
```
front: ( ○ ) body, no eyes back: ( ╲╲ ) eyes, drawn upside down spin: front, back, front, back … × 12 per second → ( ◉ ) complete bot
```

**Critical thinking:**
the zoetrope needs you to look through a moving slit, work to see the illusion. Modern screens remove all effort. Did the effort make early audiences value animation more?

**Lateral thinking:**
subway tunnel ads, strobe fountains and 3D-printed zoetrope sculptures (Pixar's, for example) still use these principles. Could a physical bot zoetrope be a desk toy or merchandise piece?

**First principles:**
what's the minimum number of glimpses per second for motion to feel continuous, and why does it differ for a flicker (brightness) versus motion (position)?

- How does a 3D-printed zoetrope sculpture work?
- How did the first film projectors use the same shutter idea?