It is not often that you come across an independent café in central London that has great coffee, a good deal of space and seats available and so I found myself very happy to have come across Timberyard near Seven Dials. As I ordered my long black, I was presented with a choice of bean for the espresso base. Should I have the “fruity and acidic” Jabberwocky, or the “chocolate” Climpsons? I was trying Timberyard for the first time and so the choice was easy. For me ‘chocolate’ will win over ‘fruity’ every time. However having the choice was a nice touch. Being in central London, it was of course crowded when I tried it, but there were still seats around, including some stools outside. I took a seat outside, ready to watch the people and the cars going by. After a short while, the coffee was brought over, served on a wooden tray together with a complementary bottle of water.
It was a very pleasant location to sit and enjoy my coffee while I watched people rushing by on their way to various meetings and tourists milling around, taking their time to soak in the city. As I waited for the coffee to cool, the crema on the surface started to break up and I was reminded of the coastline of Norway. It struck me that the same mathematics of fractals describes the coastlines as would describe the patterns in the crema. It was then that I noticed the street lighting. A light converted from an old style gas lamp was attached to the wall of a shop just across from where I was having my coffee. In the other direction, there was a modern lamp-post of one particular design and then, just slightly further down the road, a lamp-post of a different design. This prompted me to think about the history of street lighting and also the problems with it.
One of the first roads in England to be lit at night was the Route du Roi (nowadays known as Rotten Row) that ran from Kensington Palace to St James Park. Three hundred lamps were hung from trees along the route. These first street lights produced light by burning fuel, a method of street lighting which existed in one form or another until fairly recent times (as evidenced by the oldest street lamp visible from Timberyard). They were installed, as now, to try to reduce crime; it seems that the park used to be frequented by highwaymen. One of these had been hanged for the killing of a woman in the park in 1687. Though it wasn’t quite murder: Rather than be robbed of her wedding ring, the unfortunate lady had attempted to swallow it and so choked to death.
A more recent type of street light was based on sodium. Applying an electric voltage across a gas of sodium caused the sodium to emit light in the yellow region of the visible spectrum. If rather than sodium, the lights had been based on neon gas, the colour of the light emitted would have been different as the colour corresponds to the different energy levels in the atoms, (for more info click here). In an effort to find increasingly efficient light sources, there is now a move into street lighting based on LEDs (Light emitting diodes). Rather like the sodium lamps, such devices work by applying a voltage over a material but in the case of the LEDs, the material is a semiconductor junction (where the energy gap can be manipulated to have the same size as the energy of visible light). LEDs have the significant advantage that the voltage supplied to produce sufficient lighting can be much less than is the case for sodium lights. This increase in efficiency is a small but effective way to limit our carbon dioxide emissions, especially when used together with sensors on the lamp post to detect when it is dark enough to actually necessitate the light being turned on.
Such a combination of energy saving measures benefits not just the planet but the public wallet. Perhaps in a few years time we’ll see such a set of eco-friendly lamp-posts spring up near Timberyard to add to the collection of street lights there.
In the meanwhile, if you visit Timberyard and notice some interesting physics or history, or if you just slow down and see something interesting, please let me know using the comments box below.
Timberyard is at 7 Upper St Martin’s Lane, Seven Dials, WC2H 9DL (and Old St, EC1V 9HW.)
London info taken from The London Encyclopaedia (3rd Ed), Hibbert et al.