Cameron's state of the union flop

The SNP will be delighted with the Prime Minister's lacklustre speech in Edinburgh.

Even before David Cameron delivered his speech in defence of the union in Edinburgh this afternoon, the Scottish National Party had already dismissed it as "threadbare and outdated". In retrospect, the nationalists could have added "ill-informed" and "underwhelming" and they still would have fallen slightly short of the mark.
 
It's safe to say that the Prime Minister's attempt today to develop a positive case for Scotland to remain within the United Kingdom probably won't be remembered as one of the turning points in the debate about Scotland's constitutional future.
 
On the contrary, Cameron gave the distinct impression of someone who hadn't seriously examined his opponent's arguments. At times, in fact, he gave the impression of someone who hadn't really examined his own. "Scotland", he said, "is richer and fairer as part of the UK". But the facts simply don't back this up. Over the last 35 - 40 years, North Sea oil production has generated as much as £300bn in tax revenues for the UK Exchequer, yet Scottish rates of income inequality have skyrocketed while social mobility has stagnated. Only a Home Counties Conservative could describe that as "fair".
 
The emotive elements of Cameron's address were similarly unpersuasive. "The link between our nations is a precious thing. It's about our history, our values, our shared identity". Well, of course. But just because two nations share some sense of an identity it doesn't mean they should also share a government, a parliament or a constitution. Few would deny the strength of the cultural relationship between Britain and Ireland. Fewer still believe the latter should re-join the UK because of it. Indeed, from a nationalist perspective, Cameron's decision to emphasise the common historical experiences of the Scots and the English will be seen as an indication of the intellectual weakness of unionism. Alex Salmond knows that the referendum will be won or lost on political and economic, rather than sentimental, grounds. Unionists should be worried that their leaders have not yet come to the same realisation.
 
Worse still, in claiming that the provisions contained within the Scotland Bill would give the Scottish Parliament tax raising powers "for the first time", Cameron revealed his poor grasp of the details of the current devolutionary settlement. Holyrood already has the power to vary income tax rates by 3p in the pound.
 
In reality, nationalists are quietly delighted with Cameron's apparent eagerness to be involved in the referendum campaign. The Tory brand remains contaminated north of the border and, since Thatcher, attempts by the Conservative Party to influence Scottish opinion have come across as hectoring and belligerent. What's more, every trip Cameron makes to Scotland serves as a reminder of how thin his mandate in the country is. It is common knowledge that support for the Tories in Scotland has fallen steadily over the last six decades. It less well known that if the coalition survives for the duration of this parliamentary session, Scots will have spent almost as many post-war years ruled by Westminster governments they didn't vote for as those they did.
 
This "democratic deficit" was one of a number of important issues Cameron failed to mention in Edinburgh today. But why would he? Before it became apparent that the union was genuinely under threat, the Tory leader had shown little interest in -- and therefore developed little understanding of -- Scotland and Scottish affairs. That absence of understanding -- on full display earlier -- will do the unionists no favours as the 2014 vote draws closer. Don't be surprised if Salmond is already busy trying to arrange the next the prime ministerial visit.
 

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Inside Big Ben: why the world’s most famous clock will soon lose its bong

Every now and then, even the most famous of clocks need a bit of care.

London is soon going to lose one of its most familiar sounds when the world-famous Big Ben falls silent for repairs. The “bonging” chimes that have marked the passing of time for Londoners since 1859 will fall silent for months beginning in 2017 as part of a three-year £29m conservation project.

Of course, “Big Ben” is the nickname of the Great Bell and the bell itself is not in bad shape – even though it does have a huge crack in it.

The bell weighs nearly 14 tonnes and it cracked in 1859 when it was first bonged with a hammer that was way too heavy.

The crack was never repaired. Instead the bell was rotated one eighth of a turn and a lighter (200kg) hammer was installed. The cracked bell has a characteristic sound which we have all grown to love.

Big Ben strikes. UK Parliament.

Instead, it is the Elizabeth Tower (1859) and the clock mechanism (1854), designed by Denison and Airy, that need attention.

Any building or machine needs regular maintenance – we paint our doors and windows when they need it and we repair or replace our cars quite routinely. It is convenient to choose a day when we’re out of the house to paint the doors, or when we don’t need the car to repair the brakes. But a clock just doesn’t stop – especially not a clock as iconic as the Great Clock at the Palace of Westminster.

Repairs to the tower are long overdue. There is corrosion damage to the cast iron roof and to the belfry structure which keeps the bells in place. There is water damage to the masonry and condensation problems will be addressed, too. There are plumbing and electrical works to be done for a lift to be installed in one of the ventilation shafts, toilet facilities and the fitting of low-energy lighting.

Marvel of engineering

The clock mechanism itself is remarkable. In its 162-year history it has only had one major breakdown. In 1976 the speed regulator for the chimes broke and the mechanism sped up to destruction. The resulting damage took months to repair.

The weights that drive the clock are, like the bells and hammers, unimaginably huge. The “drive train” that keeps the pendulum swinging and that turns the hands is driven by a weight of about 100kg. Two other weights that ring the bells are each over a tonne. If any of these weights falls out of control (as in the 1976 incident), they could do a lot of damage.

The pendulum suspension spring is especially critical because it holds up the huge pendulum bob which weighs 321kg. The swinging pendulum releases the “escapement” every two seconds which then turns the hands on the clock’s four faces. If you look very closely, you will see that the minute hand doesn’t move smoothly but it sits still most of the time, only moving on each tick by 1.5cm.

The pendulum swings back and forth 21,600 times a day. That’s nearly 8m times a year, bending the pendulum spring. Like any metal, it has the potential to suffer from fatigue. The pendulum needs to be lifted out of the clock so that the spring can be closely inspected.

The clock derives its remarkable accuracy in part from the temperature compensation which is built into the construction of the pendulum. This was yet another of John Harrison’s genius ideas (you probably know him from longitude fame). He came up with the solution of using metals of differing temperature expansion coefficient so that the pendulum doesn’t change in length as the temperature changes with the seasons.

In the Westminster clock, the pendulum shaft is made of concentric tubes of steel and zinc. A similar construction is described for the clock in Trinity College Cambridge and near perfect temperature compensation can be achieved. But zinc is a ductile metal and the tube deforms with time under the heavy load of the 321kg pendulum bob. This “creeping” will cause the temperature compensation to jam up and become less effective.

So stopping the clock will also be a good opportunity to dismantle the pendulum completely and to check that the zinc tube is sliding freely. This in itself is a few days' work.

What makes it tick

But the truly clever bit of this clock is the escapement. All clocks have one - it’s what makes the clock tick, quite literally. Denison developed his new gravity escapement especially for the Westminster clock. It decouples the driving force of the falling weight from the periodic force that maintains the motion of the pendulum. To this day, the best tower clocks in England use the gravity escapement leading to remarkable accuracy – better even than that of your quartz crystal wrist watch.

In Denison’s gravity escapement, the “tick” is the impact of the “legs” of the escapement colliding with hardened steel seats. Each collision causes microscopic damage which, accumulated over millions of collisions per year, causes wear and tear affecting the accuracy of the clock. It is impossible to inspect the escapement without stopping the clock. Part of the maintenance proposed during this stoppage is a thorough overhaul of the escapement and the other workings of the clock.

The Westminster clock is a remarkable icon for London and for England. For more than 150 years it has reminded us of each hour, tirelessly. That’s what I love about clocks – they seem to carry on without a fuss. But every now and then even the most famous of clocks need a bit of care. After this period of pampering, “Big Ben” ought to be set for another 100 or so years of trouble-free running.

The Conversation

Hugh Hunt is a Reader in Engineering Dynamics and Vibration at the University of Cambridge.

This article was originally published on The Conversation. Read the original article.