Tag Archives: History


A bridged history of Königsberg

To mathematicians, they are the most famous bridges in the world. Spanning the river Pregel as it flows into the Baltic Sea, the Seven Bridges of Königsberg are today virtually synonymous with the field of topology, the mathematical study of shapes.

Their immortality was assured in 1735 when Leonhard Euler, the great Swiss mathematician, became intrigued by the city’s unique geometrical configuration. In addition to settlements on the north and south banks of the river Pregel, 18th Century Königsberg also included two large islands known as Kneiphof and Lomse. These islands were connected to the mainland as well as each other by seven bridges that were central to the city’s life.


Euler wanted to know the answer to a comparatively simple question: would it be possible for a visitor to cross each and every one of Königsberg’s seven bridges once and only once? Being a mathematician and not a tourist, it didn’t matter to him whether the visitor started in the same place as she finished.

Such a path, Euler eventually concluded, would not be possible. The visitor (let’s call her Doris) would either find herself stranded on Kneiphof or else forced to angrily patrol the riverbank waiting for the authorities to build her another bridge. Needless to say, Euler refused to consider either jumping or swimming as valid options.

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Hedy Lamarr

The four women my computers are named after

At the age of 13 I got my first computer: a custom-built gaming rig with a brand new dual core processor. For the first time in my life I didn’t have to share a computer with anybody else in my family — I could use it exactly how I wanted and, more importantly, I could give it whatever name I chose.

Naming a household appliance may seem like a cute affectation — only marginally better than giving a name to your favourite rock or comfiest underwear — but is a necessary part of networking. Without a hostname, computers cannot identify themselves to each other to share information. The principle is somewhat abstracted on the Internet, but essentially, the www in “www.tychosnose.com” is the hostname of our web server.

In honour of the grandfather of computing I named my first computer babbage, so it was only natural that my first laptop – one of those laptops for teenagers – obtained several years later, should then be called lovelace (read on if you don’t know why). After babbage’s retirement, however, all my devices have been named after pioneering women in computer science or related fields.

Babbage and Lovelace as drawn in 2D Goggles

Babbage and Lovelace as a crime-fighting duo in 2D Goggles, a comic by Sydney Padua.

The ‘middle’ Tuesday in October is now known as Ada Lovelace Day, an opportunity to celebrate the achievements of women in science and technology. As part of the celebrations, today I would like to share the stories of four amazing women my computers are named after.

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The Kilogram turns 125

We all know what a kilogram is, right? It’s the mass of a bag of sugar. Thank goodness for the bag of sugar. Without it we’d be forced to imagine 1/7000th of an African bull elephant or 1/14560th of a double decker bus or God only knows what fraction of the weight of Wales.

Having a clear visualisation of the kilogram is important for all sorts of reasons, not least because it’s one of the seven SI units, the fundamental alphabet of symbols which can be combined in a variety of ways to express any physical quantity. Speed, for instance, is measured in metres per second, whereas force can be expressed in terms of kilogram metres per second squared.

The kilogram was accepted into this metrological pantheon alongside the metre 125 years ago today, when the value of both units was defined at the first General Conference on Weights and Measures organised by the BIPM. As a consequence of that meeting, three identical kilograms were cast by the firm Johnson Matthey out of a mass of platinum-iridium alloy. This alloy was chosen because of its density and chemical stability, meaning that the kilograms would be both small and resistant to rust. One of the kilograms was kept at the BIPM offices in Sevres, and two were sent for safekeeping in America. Rumours that a further three were subsequently distributed to the elven-kings under the sky have no foundation in truth.

One kilo to rule them all

One kilo to rule them all

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Nobody ever said dyeing was easy

As anyone who has ever attempted to buy wallpaper with a loved one will know, colours are notoriously difficult to define. One man’s Burgundy is close enough to another woman’s Maroon for Red to be a dangerously ambiguous catch-all term.

But what if more were at stake when choosing colours than marital happiness. What if the choice of one particular shade of blue over another constituted a religious sin. And – as if that weren’t bad enough – what if nobody had actually set eyes on the colour in question since the days of Ancient Rome.

This chromatic grey area is not a hypothetical situation. The disappearance of the colour t’khelet (pronounced with a properly phlegm-filled ‘kh’, if you please) was a pressing question in Jewish theology for well over a millennium. It took generations of rabbis, dye-makers and chemists to bring the dye back from the dead, and in the process explain just how it was that the Jews first got the blues.


In the Old Testament’s Book of Numbers (chapter 15, verse 38), the Lord tells Moses to instruct the Children of Israel to “make for themselves fringes on the corners of their garments, throughout their generations, and affix a thread of t’khelet on the fringe of each corner.”

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