I came across Lumberjack last week while spending an afternoon in Camberwell looking for interesting cafes to “cafe-physics” review. I was actually on my way to a cafe further along the road when a couple of wooden structures in the window attracted my attention. Thinking that they were “Inukshuk” we decided to go in and try this new cafe. It turned out to be a good choice because, even though the structures were not in fact inuksuik, they had brought us into this lovely little cafe. We arrived shortly before closing but I still had time to enjoy a very good long black (with beans from Old Spike Roastery). Complementary water was brought over to the table. It would have been great if we had arrived just that bit earlier so that we could have had more time to properly appreciate this friendly cafe. The interior is bright and smartly decorated with wooden tables and shelving as well as plenty of seats at the back. The wooden furniture is explained by the fact that the cafe is the trading arm for London Reclaimed, a charity that provides employment and carpentry training to 16-25 year olds from SE London while making bespoke furniture from reclaimed timber. The cafe too aims to provide training and support to encourage 16-25 year olds into work and a future career. In terms of the ‘physics’ bit of this review, the interior of the cafe certainly has plenty to observe, from the pendulum like light fittings to the detail of the wood. But as this cafe is metaphorically, and in some ways literally, built on/with wood and as Lumberjack boasts on its website that “almost everything you’ll find in store, from the coffee to the furniture, are sourced as locally and homemade as possible” it is only appropriate that this cafe-physics review should focus on wood, trees and a tree very specific and local to London; the London Plane tree.
With their characteristic mottled bark, London Plane trees are a recognisable sight along many a London street. The bark absorbs pollutants from the street before bits of bark fall off, taking the pollution with them and leaving the tree with its mottled appearance. Their root structure and resistance to pruning or pollarding helps to ensure that (mostly) they can survive happily in the crowded confines of London pavements. They are indeed very much a tree that seems almost specially adapted to London. Yet the connection between the London Plane and London goes deeper than that. The first ever record of a London Plane tree was in the seventeenth century, just up the road from Lumberjack, in the Vauxhall Gardens of John Tradescant the Younger. The London Plane is in fact a hybrid tree, thought to be a cross between the American sycamore (first recorded in London in 1548) and the Oriental Plane (first recorded in London in the C17th). Both these trees were found in Tradescant’s gardens and it is possible that the hybrid tree, the now ubiquitous London Plane, was actually first grown in Vauxhall.
Even though London is full of Plane Trees, it is not very common to find plane wood furniture. Rather than the grain visible in the tables at Lumberjack, Plane wood shows a “lacy” structure that gives furniture made with plane a distinctive pattern. Although unsuitable for outdoor furniture, plane-wood can be used to make indoor furniture and indeed some London based cabinet makers have even documented obtaining usable timber from recently felled London Planes.
And it is this that takes us to the physics part of the cafe-physics review. Perhaps it is the areas (and the parks) that I walk through, but it seems to me that there has been a fair amount of tree felling in London over the last six months or so. Part of the reason for this must be to ensure that the trees in our parks and that line our streets are safe and not going to fall down in high winds. Many trees that fall down in high winds do so because they get uprooted. However it is also possible, in very high winds for the whole tree to snap. Indeed, when researchers mapped the wind speeds through a forested area of Southern France during a storm in January 2009 they found that when the wind speed exceeded ~40 m/s (90 miles per hour), more than 50% of the trees broke in the wind, irrespective of whether these trees were softwood (pine) or hardwood (oak). A very recent paper by a Paris-based group (published last week in the journal Physical Review E) confirmed that irrespective of the species of tree or the tree height, the trunks of trees were liable to snap at a critical wind speed. The team combined experiment and theory to establish that the critical wind speed scaled with the tree’s diameter and height. However, because trees generally treble their diameter as they double their height, the effect of the diameter change was (almost) cancelled by the height difference between trees. Surprisingly, this critical wind speed did not depend on the elasticity of the tree, so there is no difference between a softwood such as pine and a hardwood like oak or plane. The researchers calculated the critical wind speed needed to break a tree to be 56 m/s, very close to the 40 m/s observed in that January storm.
Lumberjack can be found at 70 Camberwell Church St, SE5 8QZ
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