When I was a kid I used to buy stuff mail order from Ellisdons in Liverpool.
They were a joke and novelty outfit and the kings of mail order fun, a bit like a British version of the Cap'n Company at the back of American monster comics.
I could write a whole blog about what I loved about Ellisdons but one of the items that came through the post was a mechanical calculator called the Chadwick Magic Brain.
Like a pocket sized version of Alan Turings famous machine, this red-plastic edge metal-faced apparatus felt and looked like a mobile phone.
The calculating came from a series of toothed recesses, in which you slotted a metal pen at the numbers you wanted to add, subtract or times and away you went. With the pen tip inserted into a tooth you drew it up or down to make the calculation, which appeared in small windows by way of cogs and dials.
It was quite magical really, in the same way the Magic Robot was magical in the way it answered questions without us really understanding how.
I'm surprised its not still with me really. Being small and slim it was easily portable through time. Maybe one of my older brothers still has it.
Do you remember this device readers? Did you have any other early calculators?