Schiehallion and the Earth’s Mass

My first Munro and nearly my last.

For those who don’t know a “Munro” is a mountain in Scotland over 3,000 feet. There are 283 of them.

On a fine summer’s day Schiehallion at 3,553 ft is a relatively easy and straightforward climb. One of Scotland’s most popular mountains some 20,000 ascend it every year. Many who do are rewarded with truly spectacular views. Schiehallion is one of those mountains whose views of it are even more beautiful than the views from it. Its very symmetry is historically significant but more on that later.

I climbed the mountain on 10th September 1978. It was certainly not a fine summer’s day.

I was attending an Outward Bound course with a party of fellow foreign staff from the Hongkong & Shanghai Banking Corporation (now known as HSBC). So essentially a captive party on an involuntary climb (a bit like a school outing really). We had travelled up (should it be down?) from London to  the Central Scottish Highlands just north of Loch Tay. As an aside I found it ironic that even though I had been to Scottish schools for some 10 years I had never before climbed a Munro or even knew what one was.

On our day it was cloudy and damp. Cold and wet we trudged our miserable and increasingly mutinous way through interminable bog barely being able to see beyond our own feet. Zero visibility and buffeting icy winds were our only rewards when at last we arrived at the summit. Not many of us were encouraged to repeat the experience. There was little sense of accomplishment and our only thought at the time was to get down as quickly as possible to our lodgings and into some dry clothes followed by a dram and a warm fire.

It was only many years later that I read (thank you Bill Bryson) that Schiehallion features as prominently in the history of science as it does in the Perthshire countryside. Its isolated position and extremely symmetrical shape led it to be selected in 1774 by Charles Mason (yes he being very familiar to Americans from the eponymous Mason Dixon Line – the symbolic cultural dividing line between the northern and southern states) for a ground-breaking experiment to estimate the earth’s mass. This is a little bit where I get lost myself but the deflection of a pendulum by Schiehallion’s mass provided an estimate of the mean density of the Earth, from which its mass and a value for Newton’s Gravitational Constant G could be deduced (got that?!). Actually Mason turned down the commission to carry out the work (being a clever man he could foresee the sort of experience that I was to encounter) preferring wisely to stay in the more climate friendly south. The work was instead coordinated by Nevil Maskelyne the Astronomer Royal. Incidentally this position still exists and the incumbent who advises the Queen on “astronomical and related scientific matters” is paid GBP100 a year.  The Astronomer Royal (I just had to repeat that marvelous title) was assisted in the task by mathematician Charles Hutton, who devised a system to graphically represent large volumes of surveyed heights. We now know the graphical system to be contour lines.

Oh I know you are positively itching to know that Hutton calculated the mass of the earth to be 5,000 million million tons (that is 5,000,000,000,000,000 metric tons). Good first objective calculation I suppose and all kudos for his trying but he was a bit out. The earth’s mass is now known to be 6.6 sextillion metric tons (that is 6,600,000,000,000,000,000,000 metric tons – so convenient to be a nice round number!).

There are good and bad climbing days and it is extremely difficult to totally avoid the latter when climbing in Scotland as the weather can change by the hour  (so ala Baden-Powell just “Be Prepared”). However I’ve now grown to appreciate the Scottish mountains whatever the conditions but when the sun comes out……….

I wouldn’t wish to give Schiehallion a bad press just because I happened to climb it on a bad day. Here is what it actually looks like on a fine winter’s day – as you can see a truly beautiful mountain:

We had another mountain to climb later that September week of 1978; Ben Alder. A slightly better experience – see my next post.


About The Weary Traveller

I like to walk up and down hills. I've been so very fortunate to have lived most of my life in the Far East (Hong Kong, Malaysia, Singapore, Thailand, Vietnam) and the Middle East (Qatar, Oman and U.A.E). I now live and work in Bangkok. I'm past the half century now and can't help but feel that some of the mountains that I've climbed lately I should have done yesteryear. The mind is willing if the legs are not always so. Here are some stories and realized dreams of hills climbed and, dales and deserts crossed. With a bit of art thrown in. I hope you might enjoy.
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3 Responses to Schiehallion and the Earth’s Mass

  1. william hannay says:

    It was popularised in the nineteenth century by the coming of the railways. If you were travelling to London, or another major terminus, you waited on the ‘up’ platform, and if you were travelling away from London, you waited on the ‘down’ platform. This is why the phrase ‘up to London’ suddenly becomes much more widespread after about 1850.
    Any other questions?

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