Friday, 25 October 2019

Quick Service

On Tuesday I went to the local post office to renew my passport. I supplied quite a small quantity of  information, surrendered my old passport and paid £90-90. (I wonder if the odd 90p buys food for the Home Office cat). Today, only three days later, my new passport arrived in the post.

My one regret is that, unlike the old one, this passport does not mention the European Union.

Wednesday, 23 October 2019

A Perverse Choice of Units

Earlier today a news broadcast included the claim that Britain has reserves of shale gas amounting to about thirteen billion cubic feet. That measurement is in several respects perverse.

The foot is an obsolete measure of length, and volume is an inconvenient measure for a quantity of gas.The volume of a gas depends on temperature and pressure, varying greatly with even quite modest changes in either, so any specification of volume should include a statement of temperature and pressure. The default values are 105 pascals regarded as standard atmospheric pressure, and 0 degrees C, though it is unlikely that natural gas would be stored under those conditions.

Mass would be a more illuminating measure. A foot is about 0.3 metres so a cubic foot is about 27 litres, The molecular weight of methane is about 16 and gram molecular volume at standard temperature and pressure is about 22.4 litres, so a cubic foot of gas would contain about:
30*16/22.4 grams = about 21.4 grams.

For 13 billion cubic feet, multiply by 13 billion, and divide by a million to convert grams to tonnes, giving: 21.4*13000 = roughly 279 000 tonnes, not such a lot!

Saturday, 12 October 2019

Forgotten Treasures

From time to time I go round the house, exploring each room in turn , looking in every cupboard, drawer and box to see what's in it. Each time I find something useful or interesting that I'd forgotten.

I'm in the middle of such an exploration now, and have already found my collection of spare shoe laces, and an old address book I stopped using about 40 years ago. The latter contains names I'd completely forgotten, including someone said to have died while laughing at the television news.