## The Addiator: Ingenious Mechanical Pocket Calculator

Growing up I loved to play with my father's Addiator, a small mechanical calculator that could easily add and subtract numbers... It wasn't a PDA but a PMA: Pocket Mechanical Assistant :-)

It's based on a very clever idea: parallel tooth metal strips had numbers from 0 to 9 printed on them, as well as a "flag" (in my addiator's case a red arrow) to indicate that you need to carry the operation over to the next column. This mechanism was originally invented in the late 1800s by a Frenchman named Louis Troncet. I've included a picture from his 1889 patent that shows you the inner working of the device. You can view a number of his patents here.

The German company Addiator manufactured devices like mine from the 1920s to the early 1980s when digital calculators finally made them obsolete. Many other companies made them too, and not just to add / subtract either

This short video shows you how simple and effective Troncet's invention was.

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## Clash of Exterior Designs: Past and Future

Though a little shocking at first, I think the juxtaposition of modern and traditional facades works pretty well in these two houses from Sion, Switzerland.

I assume that a glass (?) facade might have been a cheaper option than a full-on renovation. Wonder what the neighbors think of it? I do like the color coordinated fire hydrant in the lower left corner. Nice touch :-)

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## Great Articles on the Beauty of Maths

Earlier this year the New York Times published a great series of articles on mathematics by Cornell math professor Steven Strogatz.

Strogatz does a wonderful job sharing the wonders of maths for the lay person, starting from simple counting and finishing up with more complex topics like integration, probabilities, and some of David Hilbert's work.

Here's a beautiful example from an early column: Rock Groups. The question posed is why is the sum of consecutive odd numbers always a perfect square?
1 + 3 = 4
1 + 3 + 5 = 9
1 + 3 + 5 + 7 = 16
1 + 3 + 5 + 7 + 9 = 25

At first glance this is an interesting observation but hard to understand... Until you look at these equations graphically:

And then it makes perfect sense!

Another favorite focuses on limits and gives an elegant application to finding the area of a circle.

A series well worth reading and, if you have any, sharing with your children.
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## Golden Scarab, Golden Hair

I love insects. Many are a beautiful blend of art and science: amazing miniaturization packaged as a work of art. This golden scarab is a perfect example. No wonder the Egyptians revered them. Sadly I only got this one shot in Katrine's hair before it flew away.
Unfortunately I have no idea what kind of scarab it is, or even if it qualifies as a scarab instead of a beetle. I think it deserves the name though!

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