My blog has moved!

You will be automatically redirected to the new address, all posts have been transferred from this blog. Use site search to find them. If that does not occur, visit
and update your bookmarks.

Thursday, July 21, 2011

Book review: “At Home: A short history of Private Life” by Bill Bryson

book_at_home_ppbkI’ve been on holiday for a week, this has meant a lot of reading! Next up is “At Home: A Short History of Private Life” by Bill Bryson. A thick book arranged thematically around the rooms in Bryson’s house, a rectory in Norfolk. The links between the various rooms and the topics discussed are sometimes tenuous, such as the one between the cellar and the Erie Canal.

**I have moved my blog to, the rest of this post can be found here**

Sunday, July 17, 2011

Lead mining in the Yorkshire Dales

Bunting level: building, level entrance and hush

On a recent trip to the Yorkshire Dales we came across the remnants of lead mining; as with many things in the field these are blank discoveries with no indication of what they mean at the site. A very long time ago I did an OA level in geology, and I seem to have inherited an interest in industrial archaeology, so I resolved to find out more...

**I’ve moved my blog to, you can find this post here**


2, Nurse Cherry's Cottage**I’ve moved my blog to, you can find this post here**

In a change from usual service we went to the Yorkshire Dales rather than the Lake District for our summer holiday, this is the land of my father - whose family lived, and still live for the most part around the southern edge of the Dales. We stayed in a cottage in Reeth (2, Nurse Cherry's Cottages), recently built but in the old style. The advantage of this are that it's spacious and the plumbing was not added as an afterthought. I think the cottage was advertised as sleeping up to four people, with two bathrooms and a downstairs toilet it would take 6 pretty comfortably. We are only two, so had plenty of room. We arrived in a downpour but for the rest of the week the weather was pretty good. Reeth is a small village which was once a centre for mining and farming but now is a centre for tourism - lying in the Yorkshire Dales and on the coast to coast path. It's dominated by a large central green, although there are older buildings many are quite modern but built in the same style as the older, using the local stone.

Day 1

A pleasant walk up Arkengarthdale to Langthwaite, and back along Fremington Edge Top. The walk outwards is through pasture and many narrow styles in stone walls with little gates to prevent sheep escaping. Shortly before Langthwaite there is a footbridge across the river which takes you to a short walk through woodland before climbing up through old lead mine workings up onto Fremington Edge Top. We took the route which avoided the hamlet of Booze, considering that it was so small that it was unlikely to have a good quality sign to picture ourselves besides. Nearby is Blea Barf, and at the top of the valley on the road over into Hawse is Lovely Seat, one can't help thinking that when the Ordnance Survey visited the locals had some fun.

The walk along Fremington Edge Top is dead straight along the side of the wall. I wonder whether these walls date to the time of the old iron fence posts in the Lake District - perhaps relating to some Enclosures Act. The wall runs along the edge of wild moorland to the north and after a pleasant, if not a little windswept walk you drop back down towards Reeth.


Day 2

A route from The Green Book starting at Gunnerside, heading to Muker then up Upper Swaledale towards Keld and then back towards Muker via the Pennine Way and so along the river back to Gunnerside. Highpoints were the waterfalls at the foot of Swinner Gill and Kisdon Force. Photographers will know there is a knack to photographing waterfalls such that the water appears milky rather than frozen in time by a short exposure. The problem is this requires long exposures (about 1/2 second) and this is a bit tricky to do without a tripod - a handy rock or handrail must suffice instead. Crackpot Hall was also interesting, the term Hall is rather grandiose but the views down Swaledale were spectacular. Much birdlife to be seen including a greater spotted woodpecker, dipper, spotted flycatcher, grey wagtail, plover - no photos of these since that requires patience, speedy reactions and so forth. Lapwings all over the place.

Kisdon Force

Day 3

A more restful day today: we headed down to Harrogate and the RHS Harlow Carr garden. This is horticulture, so I'll leave the details to The Inelegant Gardener. It's a fairly lengthy drive down to Harrogate from Reeth - a little under an hour and a half. My abiding memory will be of coffee and Fat Rascal in Betty's Tea Rooms, attached to the gardens but not providing a route in or out. After a morning at Harlow Carr we headed back home via Richmond: a rather smart little town on a steep hillside with a huge castle (and more waterfalls). The Market Square would be spectacular if it weren't for a flotsam of cars which spoil any photo. Sharon and I both seem to suffer from a list which prevents the photography of buildings without post-processing. A balanced diet today of Fat Rascal, sausage roll and icecream, available from the icecream shop in Reeth a mere 100 yards from our door (via shortcut).

Richmond Castle

Day 4

Back to walking, this time one of my own devising. Starting from Gunnerside we headed up Gunnerside Beck until we reached the lead workings at Melbecks Moor. There a several sets of ruined buildings and mine tailings as you head up the valley. After climbing up through the surface workings we got onto the moor top where were visible grouse, grouse grit stations (where they can pick up grit for their gizzards) and grouse butts from where they can be shot at. You have to get pretty close to grouse before they break cover. Finally, we dropped down into the valley where we got a little lost (and quite badly nettled) trying to find the path through Rowleth Wood. Once on the path through the wood, which is narrow and overgrown, we were further nettled and as I write now a couple of hours later my legs are still tingling from the knees down.

After our walk we visited the Swaledale Museum, which although small was highly informative on the local mining industry - a subject I shall return to in another blog post.

Stonebreaker, with Sharon in background

Day 5

Over to Wensleydale for our walk today (from the Green Book), from Bainbridge up to Semer Water (a rare natural lake in the Dales) and then onwards and back via the Roman Road. The Roman Road was very straight, and as usual somewhat disappointing - it requires a great deal of imagination to call up the requisite Roman soldiers. The weather was rather better than yesterday which was overcast and prone to the odd shower; today it is a little cool out of the sun.

Wensleydale from the Roman Road

Day 6

Final day, today we went back to Wensleydale for a walk from the Green Book starting at Aysgarth Falls and taking in Bolton Castle. The Falls are a bit of a disappointment, the approved viewing locations are a little distant from the falls and are rather confined. Richmond falls offer something similar, with slightly peaty-brown water cascading over flat slabs, but with much better access. Bolton Castle, on the other hand is rather impressive, visible on the valley side for many miles it is a solid, square chunk of masonry. It was built for Richard de Scrope in 1379, and is quite substantially intact.

Bolton Castle

The Yorkshire Dales are quite different from the Lake District: the peaks are less peaky, the valleys wider and more gentle, although the moors can be bleak when the wind blows and the clouds come down. There are also a lot of picturesque waterfalls, not in the style of the Lake District which tend to be frenzied plummets down ravines but cascades over broad rocky shelves. Villages like Hawes and Reeth can get quite busy as the day goes by but out walking we scarcely saw a soul. The stone walls are all pierced with small stone stiles, which have been the distinguishing feature of this holiday.

Stone Stile

More photos here.

Friday, July 15, 2011

Book review: “In defence of History” by R.J. Evans

**I’ve moved my blog to, you can find this post**

evansI've been interested in the history of science for some time, as a result of hanging around with historians on twitter I have been led to historiography - the study of history and its methods. This has brought me to "In Defence of History" by Richard J. Evans. It provides an opportunity to compare the ways of the historian with those of my area of science.
In his introduction Evans makes clear the book is a response to postmodernist criticism of historical practice. I was also amused to note that he cites a source as saying that historians were resistant to philosophising about their subject and criticism of their methods. As a scientist it sometimes feels as if other academic disciplines, such as philosophy and history, are on a crusade to "help" science with their criticism - this has never felt at all supportive or helpful. What this book makes clear is that one shouldn't lump all such outsiders into one hostile blob!
It becomes clear through the book that postmodernism is not really a single thing. The core is the idea that all things are text, and that an external, objective world is less relevant - this idea originated with linguists and philosophers who were relatively unconcerned with the external world. As a somewhat hostile outsider Evans probably does not provide the best introduction to postmodernism, although he does acknowledge that ideas from postmodernism have been useful in the study of history and historical study.
As a by-product of this defence Evans gives a clear survey of what history is and what it claims to do.
The book begins with a history of history: raising first pre-modern styles of history, such as the chronicle and the morality tale of Gibbon's "Decline and Fall of the Roman Empire". Leopold von Ranke is cited as the father of the modern method, that's to say the inspection of contemporary documents in the historical record using them to identify causes for historical events and "facts". Here the distinction is made between the primary sources and secondary sources. For Ranke the key subject of history was politics, a view that held sway for many year but more recently has been receding. The key to the historical method therefore is hunting down original documentation and reading it with a mind to its original purpose and the context of other documents of that period with a care not to be caught out by changes in language and unspoken purposes.
Evans also identifies the crisis in history following the First World War, a stark reminder to historians that predicting the future was tricky although Evans does not sign up to the idea that history is at all about predicting the future. There's an interesting parallel here between Toynbee's "A study of history" which tried explicitly to make laws of history for predicting the future and Asimov’s Foundation series of novels, which are based on precisely this idea. Predicting future events sets a high barrier for successful prediction, some fields of science face similar challenges such as in seismology - we can say an awful lot about earthquakes but exactly where and when are not amongst the things we can say. For these fields it's typical to talk about the probabilities of events and the statistics of large numbers of events.
One thing that struck me was the statement that history was a scientific, imaginative and literary exercise, the first two are things that a scientist would sign up to for their own field immediately, but literary? For sciences such as the one I trained in, physics, students are scarcely asked to string words together. Exam questions are largely a case of putting a sequence of calculations together. My own writing is a reflection of this lack of training.
At one point Evans spends time trying to motivate the idea that history is a science, this seems to me an empty discussion - once you've decided whether or not history is a science what are you going to do? Put on a labcoat?
Since Ranke's time history has diversified immensely with the increasing focus on non-political history such as social history and an appreciation of a wider range of themes , I find this liberating since my interest in history is primarily in "people like me", therefore social and scientific, rather than political.
In contrast to any scientific research I know the political beliefs, defined broadly to include race, gender and sexuality, have a strong bearing on historical research with fields driven to support currently political agendas and the political leanings of the researcher a subject of comment. The same goes for nationality with many European historians focused very much on their own nations and with a distorted view of their importance. It's very difficult to find parallels in scientific research, to stretch a point you can perhaps look at genetic and brain imaging studies of homosexuality. There is a degree to which there exist national styles of scientific research which have varied with place and time but this research driven by the political agendas of the researcher feels alien to a scientist.
When doing battle with the postmodernists the work of a scientist is easier than that of a historian, since ultimately the usefulness of science is measured by tangible outputs, by impact. If postmodernism increases tangible outputs then it is welcomed into the fold, if it doesn't (and I don't believe it does) then it isn't. Science is tied down by reality which is always there for a return visit, with new methods, in case of dispute. History on the other hand is always flowing past, with no chance of return.
An interesting note on style is the forthright criticism of other historians through the book, and also in the afterword where he addresses his critics in detail and at length. This type of writing is rarely seen in science, that's not to say the thoughts do not exist just that such discussions are left to the bar, or other informal locations.
I found this book immensely thought provoking because it describes the inner workings of history from the point of view of a practioner, making a striking contrast with my own workings as a scientist.

Wednesday, July 06, 2011

The Two Cultures

**I’ve moved my blog to, you can find this blog post here. **

It feels that there are two cultures growing up in the world of work, that of the public and the private sectors. If you believe reports in the news, public sector workers have gold-plated pensions and vast salaries for which they do very little, and the private sector is filled with the venial moneygrabbers who can provide no service to the public, and are actively intent on harming them.

I worked in the almost-public university sector, and now in the private sector – albeit in a very large company. The similarities are quite striking: both are subjected to continual change as the result of the appointment of a new ruling clique, and often operate in Byzantine bureaucratic systems.

These days, in the private sector, my tenure is clearly not secure and never has been, despite continuing success the number of people employed in my company has decreased by over a half since 2000. I receive a bonus, or variable-pay, it is variable and it is not pensionable. 

Last week many public sector workers were on strike over their pensions.

Comparisons with private sector pensions miss the point: in the public sector 90% of full-time workers have a pension, in the private sector only 43% of the full-time workforce have a pension [source]. The glib answer to this is that we should attempt to improve the pensions of all workers. However, we should understand why pensions are not a given in the private sector.  

Consider the nature of the organisations involved: the UK government has been around for hundreds of years, and we can anticipate it will do so similarly for hundreds of years. It also has a good credit record, if we are owed money by the government there is a good chance that we’ll get because at any time the government has a sizeable tax base on which it can call. As employees of the government we can expect substantial job security. A pension plan based on 1/80ths of income accrued per year actually seems a plausible bet: you can still expect to serve a substantial fraction of that with one public employer. It’s not the same in the private sector.

For most companies 40 years is an unimaginable period of time, as it is for their employees. In 40 years many successful companies will have lived out their lives, only a few such as the one I belong to, last longer. In the recent past private pension funds have collapsed leaving their members with nothing. As a university lecturer I could quite reasonably look forward to being employed as a university lecturer for the rest of my working life. As an industrial research scientist my time horizon is about 5 years, and actually it is entirely plausible that we will all be called to a meeting tomorrow to discover that the site I work on is to be closed.

That’s the deal for big organisations, public and private but there is a third group: Have you tried to get a plumber, or similar skilled, self-employed worker recently? If you have you’ll have found that they’re remarkably available at the moment, that’s because they have no work and when they have no work they don’t get paid. The same is true for many small businesses and self-employed people. It’s not like my job, or any job in the public sector where there may be a pay freeze for for a few years. For these people recession and a drop in the GDP doesn’t just mean a pay freeze, it means a substantial drop in income – that’s what a drop in GDP is, it really means that a whole load of people are getting noticeably less than they did the previous year. The recent recession in the UK led to a drop in GDP of around 5%. The effects on me, in a big company, and those in the public sector are relatively small, so the impact on this other group are larger than the headline.

Meanwhile the company I work for is attempting changes to our pension scheme: a few years ago the final salary scheme was closed to new entrants, this year they have proposed to close the scheme for current members. The company’s stated policy is to go towards a defined contributions scheme, although that hasn’t happened yet. For people like me this means an expected loss in the value of their pension of around 20%. So, despite some misgivings as to the use to which they put their political fund (of which I will attempt to opt-out), I have joined the union.

Power to the people!

Sunday, July 03, 2011

Computational Photography


** I have moved my blog to, you can find this post here**

Lytro, Inc, a technology spin-off company founded by Ren Ng, have been in the news recently with their announcement of a re-focusable camera: take one “image”, and change where the focal plane lies after the fact. This is illustrated in the images above, generated from a single shot from the prototype camera. As you move from left to right across this sequence you can see the focus shifting from the front left of image to back right.I saw this work a few years ago at the mighty SIGGRAPH conference, it comes out of a relatively new field of “computational photography”.

All photography is computational to a degree. In the past the computation was done using lenses and chemicals, different chemical mixes and processing times led to different colour effects in the final image. Nowadays we can do things digitally, or in new combinations of physical and digital.

These days your digital camera will already be doing significant computation on any image. The CCD sensor in a camera is fundamentally a photon-counting device – it doesn’t know anything about colour. Colour is obtained by putting a Bayer mask over the sensor, a cunning array of red, green and blue filters. It requires computation to unravel the effect of this filter array to make a colour image. Your camera will also make a white balance correction to take account of lighting colour. Finally, the manufacturer may apply image sharpening and colour enhancement, since colour is a remarkably complex thing there are a range of choices about how to present measured colours. These days compact cameras often come with face recognition, a further level of computation.

The Lytro system works by placing a microlens array in the optical train, the prototype device (described here) used a 296x296 array of lenses focusing onto a 16 million pixel medium format CCD chip, just short 40mmx40mm in size. The array of microlenses means means that for each pixel on the sensor you can work out the direction in which it was travelling, rather than just where it landed. For this reason this type of photography is sometimes called 4D or light-field photography. The 4 dimensions are the 2 dimensions locating where on the sensor the photon lands, and the direction in which it travels, described by another two dimensions. Once you have this truckload of data you can start doing neat tricks, such as changing the aperture and focal position of the displayed image, you can even shift the image viewpoint.

As well as refocusing there are also potentially benefits in being able to take images before accurate autofocus is achieved and then using computation to recover a focused image.

The work leading to Lytro was done by Ren Ng in Marc Levoy’s group at Stanford, home of the Stanford Multi-Camera Array: dispense with all that fiddly microlens stuff: just strap together 100 separate digital video cameras! This area can also result in terrible things being done to innocent cameras, for example in this work on deblurring images by fluttering the shutter, half a camera has been hacked off! Those involved have recognized this propensity and created the FrankenCamera.

Another example of computational photography is in high dynamic range imaging, normal digital images are acquired in a limited dynamic range: the ratio of the brightest thing they can show to the darkest thing they can show in a single image. The way around this is to take multiple images with different exposures and then combine together. This seems to lead, rather often, to some rather “over cooked” shots. However, this is a function of taste, fundamentally there is nothing wrong with this technique. The reason that such processing occurs is that although we can capture very high dynamic range images, displaying them is tricky so we have to look for techniques to squish the range down for viewing. There’s more on high dynamic range imaging here on the Cambridge in Colour website, which I recommend for good descriptions of all manner of things relating to photography.

I’m not sure whether the Lytro camera will be a commercial success. Users of mass market cameras are not typically using the type of depth-of-field effect shown at the top of the post (and repeated ad nauseum on the Lytro website). However, the system does offer other benefits, and it may be that ultimately it ends up in cameras without us really being aware of it. It’s possible Lytro will never make a camera, but instead license the technology to the big players like Canon, Panasonic or Nikon. As it stands we are part way through the journey from research demo to product.