Bright Lights at Bloomsbury Coffee House

Bloomsbury coffee house sign

A wooden sign advertising a coffee house. What makes a modern coffee house?

The coffee houses of the eighteenth century were places where ideas were debated, new innovations created and, of course, coffee consumed. What would a modern day equivalent look like?

Bloomsbury Coffee House is in a basement on Tavistock Place. It is ideally located close to a few universities and was busy but not crowded when we arrived one afternoon during the week. There are two large rooms forming the café with several tables and artwork dotted around the room. In the warmer months, there are also a couple of tables outside in the little terraced area by the steps leading down to the basement. Many people inside that day were on laptops (there is free wifi), some were involved in conversation either with each other or through the laptop. Presentations were being discussed, new ideas bounced around. It is possible that sometimes, when thinking about past coffee houses we can be tempted to focus on what has been lost (in terms of conversation and debate) rather than what has been retained in a modern manifestation (such as idea creation and discussion via Skype, from within the coffee house). At the Bloomsbury Coffee House that day I had an espresso (Allpress) and a cinnamon bun while there were also a variety of milks on offer for other espresso based drinks. These were all a significant improvement on the coffee that was served in the establishments of the past.

lattice structures ceiling bloomsbury coffee house

A 2D square lattice pattern on the ceiling. But what is the smallest repeating pattern that you can see? Is it centred on the large squares or the small squares?

Each table was individual, some reminding me of old school desks, while the ceiling was plastered with a 2D square lattice pattern. Staring at the ceiling, prompted the question, was it the large squares or the small squares that formed the repeating unit of the structure? Quickly this made me think about Polonium. When thinking about how atoms form 3D crystal structures, we sometimes naively draw a cube with an atom at each corner. In fact, this arrangement (the simple cubic structure) is quite unstable (try stacking oranges on top of each other so they form a cube) and, for elements that do form into cubic crystal structures, a more common form of base unit is a so-called face centred or body centred cubic. One element that does form a simple cubic structure though is polonium, an element that is probably more famous for being the poison used in the Litvinenko case a few years ago.

However, an alternative train of thought was suggested by the blackboard on one of the walls of the room. A colourful message announced that the Bloomsbury Coffee House had won a Time Out Love London award. The writing, in red and blue, was a little tricky to read from the back of the room. With the lighting, the red appeared slightly brighter and more visible than the blue. Perhaps coincidentally, this is the correct way round (in terms of order of brightness) for an odd optical effect that happens as the light fades towards evening (and, in a connected manner, why it is hard to find a matching pair of socks in the dark).

writing on the wall

The blackboard at Bloomsbury Coffee House

In order to ‘see’, the eye uses a series of cells called rods and cones. The rods are the more light sensitive and more plentiful (there are more than 100 million in a human eye) but they do not have any mechanism to detect colour. Instead, they show a good response over the entire visible range with a peak response rate at ~507 nm¹ which corresponds to a blue wavelength. The cones by contrast give us the ability to discern colour. We have blue, green and red sensitive cones which show responses that peak in the blue, green and red parts of the visible spectrum respectively. The problem with the cones is that they do not respond very well in low level lighting conditions. Hence, during the day, in normal lighting conditions, the cones are active and our eyes (usually) show a peak response to yellow-green light at 555 nm. As the light falls and twilight and darkness comes in, the cones cease to work leaving only the rods so our eye’s peak response shifts to light with a blue wavelength. Subsequently, a bright red rose seen during the day may appear dimmer than the green leaves in the evening. A sea of blue and red flowers may shift from appearing bright red to bright blue as night falls.

Unfortunately, Bloomsbury Coffee House closes at 6pm which, during summer, is too early for us to see whether we can see this effect ourselves. But if you are lucky enough to have access to a garden or park where there are red flowers and are able to sit and watch them as night falls, do observe and see if you can see this shift in apparent brightness for yourself.

Bloomsbury Coffee House is at 20 Tavistock Place, WC1H 9RE

¹The Feynman Lectures on Physics, Vol I

Pushing it at Lever and Bloom, Bloomsbury

Lever Bloom coffee

Lever and Bloom under a blue sky.

Does a take-away need to be rushed? A coffee so quick that there is ‘not enough time to prepare a flat white’? Are we always so preoccupied with the distractions of our day that we consume our coffee merely for the pleasant caffeine kick that it provides?

Lever and Bloom in Bloomsbury is a great example of why this does not have to be, indeed should not be the case. Since 2015, Lever and Bloom have been operating out of a cart on Byng Place close to UCL and a number of other research institutes. The character of the surroundings really does affect the space and both times I have been to Lever and Bloom I have either met interesting people in the queue or overheard snippets of intriguing conversation about history I know nothing about.

Coffee Bloomsbury reusable coffee cup

Long black in a keep-cup and telephone box in Byng Place.

It is easy to spot the coffee cart in the corner. Firstly, it is bright red and quite eye catching but secondly because of the queue forming in front of it. Don’t be put off though, the queue moves very quickly so you won’t wait long even if you are in a rush. Queueing however does give you an opportunity to peer into the cart. Space is used extremely efficiently. with each piece of equipment  apparently having its own perfect home. It reminded me of a childhood game of trying to fit in as many objects as possible into a matchbox. A cabinet on the table in front of the cart displays cakes including cinnamon rolls (sadly sold out by the time I arrived in the afternoon). It was also nice to see the number of people ahead of me in the queue who were using re-usable cups.

The lever of the name refers to the (Izzo Pompei) lever espresso machine that is used on the cart. It was fascinating to watch the ground beans being carefully tamped and the lever being pulled to prepare the espresso. Although there is some debate as to the optimum water pressure needed for preparing an espresso, the standard pressure is 9 Bar; water is pushed through the tamped grinds at nine times the atmospheric pressure at sea level. Watching these espressos being prepared reminded me of preparing ceramic samples of an interesting magnetic material a few years ago. We were interested in the electrical properties of a class of materials called manganites. To prepare the materials for measurement we first had to grind the pre-cursor powders (but with a pestle and mortar, no burr grinders) and then, after a couple of further preparatory steps, press them into a pellet ready for firing in the oven. The machine used for pressing the pellets had a lever, not dissimilar to that on the espresso machines and yet, the pressure that we used for the pellets was roughly 1000 Bar. This high pressure was needed so that dense pellets of manganite material would be formed when we heated it in the oven (typically at 1200 ºC). Just as a good espresso depends on the pressure and then the temperature and time of extraction, so the properties of the pellet would be affected by the pressure and then temperature and time of firing in the oven.

Portland Stone fossils

Fossils in Portland Stone. It is astonishing what is revealed when you slow down and notice the buildings around you.

Similar effects affect the rocks of the earth, something that is particularly visible in the area around Lever and Bloom. A geological walking tour around Byng Place, Tottenham Court Road and towards the British Museum illustrates this particularly well. Behind Lever and Bloom, the church of Christ the King is built from Bath Stone. An oolitic limestone, this type of rock is formed of compressed sand and bits of shell. Much as the manganite samples of my study before they were fired in the oven but of a more interesting colour. Heading towards Gower St and the impressive UCL building is made of Portland Stone. Another limestone, this building material is a goldmine for urban fossil explorers. Continuing the walk, on Tottenham Court Road, the Mortimer Arms pub is fronted by quartzite while Swedish Green Marble adorns 90 Tottenham Court Road. Quartzite and Marble are both types of metamorphic rock, formed by pressing together different precursor materials at high pressure and temperature. Other types of marble can be seen on the tour, suggesting the influence of pressure and temperature of formation on the rock structure as well as the type of precursor rock.

It would seem that such a walking tour is perfectly timed for a longer style of coffee, perhaps a latte (in a re-usable cup of course) from such a centrally located place as Lever and Bloom. And of course, assuming you are using a re-usable, there is even more to ponder. The pressure and temperature during the manufacture of the re-usable cup would have affected the properties of the cup (or in my case, glass).

Let me know if you spot any interesting rocks or fossils during your time at Lever and Bloom but whatever you do, I hope that you can enjoy your coffee and then slow down to enjoy it a bit more.

Lever and Bloom is at Byng Place, WC1E 7JJ

Wonders of the World at Espresso Base, Bloomsbury

Hasten coffee, long black, black coffee, espresso base

‘Has Bean’ coffee at Espresso Base

Espresso Base is exactly the sort of café that you want to make sure that you know about, but part of you is selfishly quite happy if not too many others do. It is not that the the place is small, far from it. There is plenty of space in the courtyard at Espresso Base, beside St George’s Church, to sit and enjoy your coffee. The thing is, it is great to have the place almost entirely to yourself. With few others around, the oasis-like quality of the place is emphasised, astonishing as it is so close to the busy Bloomsbury Way. Only this oasis serves great coffee. Their coffee is roasted by Has Bean, which I admit is the reason that I first dropped into Espresso Base a few weeks ago. The black coffee that I had was certainly very good and the environment in which to enjoy the coffee was thought provoking which, for me, is an important aspect of any café. Cafés need to be places that you can go, slow down and notice things and Espresso Base certainly falls into that group of cafés that I would highly recommend both for the coffee and the café.

stone recycling, slate, slate waterfall, geology

The purple slate waterfall feature in the courtyard area at Espresso Base. You can just see the stone with the rectangular holes carved into it at the bottom of the wall.

On the day that we arrived, it had been raining. For a café with seating outside this may have posed a problem but the chairs had been thoughtfully folded so that they remained dry. The rain had however seeped into some of the paving slabs around the chairs and so that was the first thing to notice, the fact that many objects when wet appear darker, why? Opposite our seating was a rock feature that to me looked like a waterfall made out of slate, the slate had a purple tinge which again, had been made slightly more purple by the rain. Below the slate ‘waterfall’ and forming a wall, were a series of stones that had clearly been taken here from somewhere else. I say ‘clearly’, because the stone at the bottom had two holes that had been carved out of it, one square, one slightly more rectangular. Presumably the stone had been used as part of a gate post in the past and yet there is no evidence of the remains of a gate on the other side of the courtyard (I think that a gate post would have to be deeper than the square indent in the paving slab that is at the other side of the courtyard). It is therefore more likely that the stone had been used somewhere else beforehand and ‘recycled’ for use in this wall. This juxtaposition of slate above and recycled stone below reminded me of the early geologists and how they identified the Great Glen fault that runs through Loch Ness in Scotland. Slate is a metamorphic rock, meaning that it has undergone changes due to the high pressure and temperatures within the Earth. Slate is however quite a low-grade metamorphic rock so, compared with higher grade metamorphic rocks, it has not been subjected to that much pressure or that much temperature. By mapping the lower grade and higher grade metamorphic rocks along the Great Glen, the early geologists noticed a line that sharply separated the metamorphic rock types. This fault would have, in the past, caused earthquakes as the ground slipped along the fault.

Replica of Mausoleum of Halicarnassus

The steeple of St George’s church, Bloomsbury Way. The statue on top is of King George I rather than King Mausolus in  his chariot. The statue of Mausolus, his wife/sister Artemisia and a horse from his chariot can be seen in the British Museum.

On leaving Espresso Base I turned and looked up at the church. If you get a chance, take a look at the steeple. Particularly ornate, the stepped steeple is apparently built to the description of the Mausoleum of Halicarnassus by Pliny the Elder. This monument was one of the seven wonders of the Ancient World and was built to be the burial chamber of King Mausolus of Karia. Described as standing approximately 40 m in height, this massive stepped, marble pyramid stood on top of 36 columns surrounded by statues. Topping the pyramid was a statue of King Mausolus himself, in a chariot. This ancient wonder is thought to have been destroyed by an earthquake in the fourteenth century after which the stones were ‘recycled’ by the Knights of Malta to build a fortress. A history that is aptly mirrored in the geology and stone recycling evident in the courtyard of Espresso Base.


Espresso Base can be found in the courtyard of St George’s church, Bloomsbury Way, WC1A 2SE

Artefacts from the Mausoleum of Halicarnassus can be seen in room 21 of the British Museum (conveniently just around the corner from Espresso Base).

Geology help from: “Geology Today, Understanding our planet”, Murck/Skinner, John Wiley & Sons, 1999