Remembering a favourite toy
If you were to have asked my mother what was my favourite toy she would probably have told you that it was an old kettle. Like most children, I played with all manner of different objects.
We had a relative who worked for Slazenger so we had a constant supply of reject tennis balls. Our house had a high wall that was perfect for catching practice. I’d spend hours throwing a ball at the wall and catching the rebound. But it was the humming top I received for Christmas one year that I would have to nominate as my favourite.
It was a brightly coloured hollow steel sphere with extensions at top and bottom. The extension at the bottom provided a rounded point on which it spun. The upper extension was pierced by a narrow slot. Both extensions contained holes around their sides. A twisted piece of flat metal fitted in the slot and was topped by a wooden handle.
If you pushed the handle the piece of metal would passed through the slot into the sphere causing the object to rotate. The harder you pushed the faster it would spin. As the speed of rotation increased the note emitted by air passing over the holes increased. The colourful illustrations of animals and butterflies on the outside of the sphere disappeared, replaced by a rainbow of multi-coloured lines.
If you let go the handle, coriolis force would cause the top to wander away from you. As it slowed down it would start to wobble. The trick was to keep up with the wandering and, grabbing hold of the handle, pump up and down to increase the speed of rotation before it started to wobble.
Looking back now, I wonder of I should have been curious about the science behind its operation: why pushing the twisted metal into the slot caused the object to rotate; why it hummed – I know now that it was air passing across the holes, like someone playing a flute; why it wandered and wobbled. I guess I was too young to contemplate these things. I was simply entranced by the magic of the colour and sound.