265.296 Metres

To kick off my series about length measures and the Google Maps DMT, I decided to start with one of the more common (and, arguably, useful) units on offer: the metre (m).

The metre (or meter to our American cousins) is one of the seven basic units of the SI system of measurements favoured by the world scientific community, which is the modern form of the metric system.

There have been several definitions of the metre since it was first proposed by English philosopher John Wilkins in 1668.  Apparently Wilkins proposed setting 1m to be the length of a pendulum with a half-period (IIRC that’s the time taken to swing from one extreme to the other – a full period being the time to complete a swing there and back again) of 1 second.  During the eighteenth century this original definition vied with another that defined the metre as one ten-millionth of the length of the Earth’s meridian along a quadrant (that is the distance from the equator to the North Pole) at sea level.

When the French Academy of Sciences defined their metric system in 1791 (around the time of the French Revolution), they opted for the latter definition, since the length of the pendulum required to give a 1s swing is affected by the slight variations in strength of the earth’s gravitational field at different location while the length of the meridian is constant (assuming, of course, you can measure it with sufficient accuracy in the first place).  As far as I can tell, this was the first official definition of the meter.

For nearly a century, from 1875, the length of the metre was defined to be the length of a specific metal bar measured under specified conditions (the gory details, along with a lot more information about historical definitions of the metre, can be found in the Wikipedia article linked above).  This was replaced in 1960 by a definition based on the wavelength of a particular line in the emission spectrum of Krypton-86 in a vacuum (presumably a constant for all Kr-86 atoms and therefore a, theoretically, more easily transferable measurement than the length of a single metal bar kept in Paris).

In 1983 the current definition of the meter was agreed, namely the length of the path travelled by light in vacuum during a time interval of 1  ⁄   299,792,458 of a second.  This is, of course, dependent on the definition of a second (which I won’t go into now, as this is supposed to be an article about length measurements) and the constancy of the speed of light in a vacuum (one of the cornerstones of Einstein’s theories of Relativity).

As an SI unit, the metre comes supplied with a whole bucketload of standard prefixes to denote decimal multiples of the basic unit.  This means that you can write distances from the very small (e.g. the diameter of a helium atom is about 0.0000000001m or 0.1nm (nanometres)) to the very large (e.g. the diameter of the sun is about 1,400,000,000m or 1.4GM (gigametres)) without excessive leading or trailing zeroes.  For everyday purposes, kilometres (1,000m) and millimetres (0.001m) are especially useful.

The span of the Menai Suspension Bridge (shore to shore, as measured using the Google DMT) is 265.296m.  My regular commute to work (using approximate start and end points, measured using the Google Maps navigational tools and my usual route) is 4.2km.

A Bridge How Far?

A few years ago, while playing around with Google Maps, I stumbled across an exciting experimental feature which is still available (evidently still experimental and definitely still quite exciting) – the Distance Measurement Tool.  To enable this you have to go to Google Maps Labs (a button just above the copyright information on the left-hand side of the Google Maps screen, at least how it appears on my browser today) and select the tool.  It then puts a small icon showing a picture of a ruler at the bottom left of the map screen.  Clicking on this activates the tool.

The DMT enables you to measure the straight-line distance between points on the map, allowing you to string several points together to approximate any path.  You have to put the points in manually and there doesn’t seem to be any way of editing any but the first and last points, which slightly limits its usefulness, but it is still quite fun to play with and does enable you to measure distances between things that are not on the roads (which you could measure using the navigation tools).

In its default mode, the tool gives you a choice between metric and English (aka Imperial, i.e. miles, feet and inches etc.) measurements.  However, next to the unit selector there is a link which, as I recall, used to be labelled Geek Mode and is now called I’m feeling geeky.  If you click on that, it replaces the brace of radio buttons in the unit selector with a drop down list containing an impressively long collection of units ranging from the commonplace (inches, yards or miles), through the well-known but not used every day (except perhaps by astronomers or other specialists – things like light years or Didot points) to the decidedly obscure (beard-seconds or Jewish second temple sacred cubits).

Over the next few weeks, I thought it would be quite fun to write a series of posts exploring some of the units that are available in the Google Maps DMT.  In each one, I will focus on a single unit (or perhaps a series of related units) and see what information I can find out about it (or them).  To give a useful point of comparison I will, each time, state the length of the span of the Menai Suspension Bridge (shore to shore as it appears on the Google map) in the chosen unit of the day.

There are two reasons for choosing this specific landmark.  One is that I cycle (or walk) across this bridge on my way to and from work every day, and it was the most convenient section of my daily commute (where I hatched, or at least developed, the idea for this series) to clearly define and  measure on the map.  The other is its special relevance (by virtue of being a bridge, rather than this specific bridge) for one of the units to appear at some point in the series – you’ll just have to keep reading to find out which.

There is a version of the DMT on the Google Maps for Android app, but that one doesn’t appear to have a geek mode.  Indeed, I haven’t yet figured out if it’s even possible to get it to work in metric. 😦

NB in case you were wondering, the title of today’s post is inspired by the film A Bridge Too Far, which Wikipedia describes as an “epic war film”, although I don’t think I’ve ever actually seen it.

Hooligans in Holyhead

Last Saturday I had a gig with The Rice Hooligan Orchestra at a pub in Holyhead.  This was our first gig since we played the Conwy Food Festival last October.  We’ve got another one coming up in a fortnight but otherwise our calendar for this year is, so far, empty.

It was good to be playing again and, despite the interval since our last gig, I could still remember most of the songs reasonably well.  Unfortunately, as I don’t regularly look after Claudia (the borrowed double bass I play in the band) and therefore don’t get much opportunity to practice, the heavy strings took their toll on my plucking fingers and I’m currently sporting a nice pair of blisters.  They should just have time to go down before the next gig!

Crystallised Ginger and Gathia Mix

I forgot to take my lunch with me when I went in to work this morning.  Fortunately, I did have my wallet with me as I hoped to be able to pick up some herbs and spices that I wanted when I dropped down into town for a meeting, so I was able to buy some things to eat at lunchtime (just as well, too, as the herb buying was a bit of a non-starter – lemongrass doesn’t seem to be sold by many shops round here and cinnamon sticks appear to be undergoing a surge of popularity, judging by the fact that all the shops seemed to be sold out of them).

One of the things I got was a packet of Gathia mix, which looked similar to Bombay mix but was quite a bit cheaper (it was on special offer).  Although I suspect I’ve eaten it before, I wasn’t aware of having done so.  According to Wikipedia it’s similar to Bombay mix but generally a bit spicier and containing fewer bulk ingredients (as opposed to spices); it’s also called Gujarati mix, which presumably indicates where it’s from.  In any case, it’s very tasty.  I haven’t had Bombay mix type things for a while and forgotten quite how much I like them.

The other exciting thing was a bag of crystallised ginger.  That too is very tasty, although probably not all that healthy given how much sugar is in it.  I seem to recall that chocolate-coated crystallised ginger is particularly nice, so I might see if I can pick up a bar of dark chocolate to melt and dip some of the remaining ginger in it.

Dancing Vikings

I have been a member of the Caernarfonshire and Anglesey Caledonian Society for several years now (probably about 7;  as mentioned in my recent post about this year’s Burns Night celebrations, I’ve been the chairman for about 3 years).   I gather that in the past, the society used to do quite a range of activities, all geared towards celebrating Scottish culture and bringing Scottish expats and other interested parties together.  In recent years, however, the main focus has been on Scottish Country Dancing.  In fact, apart from the Burns Night dinner, this is about our only regular activity (and it was the reason I joined in the first place).

We meet for dancing on Thursday evenings during the autumn, winter and spring (taking a long summer break, usually from May to mid-September) at Canolfan Penrallt in Bangor.  Our main aim, which we usually achieve, is to have lots of fun while dancing, rather than to do all the dances perfectly (although we do try and make them look reasonably nice).

As well as working through our regular repertoire of dances and trying out occasional new dances (or ones so old and long-forgotten that they are effectively new to us), we often have a slightly more complicated dance that we work hard at for several weeks in a row.  The one we’re doing at the moment is an interesting 4-couple longwise reel called The Viking Longship that is supposed to visually describe the shape of the eponymous vessel.  It’s one of those dances where the dancing couple (the first couple, as in most longwise-set dances) are doing one thing while the other couples (at least 2 of them) are doing something else for a large chunk of the dance.  In this case it involves the dancing couple nipping through rapidly vanishing gaps between the other dancers and it’s a great test of one’s phrasing abilities!

There appears to be a similarly-named but entirely unrelated dance called The Viking Ship, which we haven’t yet tried.


Tripping hither and thither

I’ve just got home from my fourth rehearsal for Iolanthe. Tonight we went through the first part of Act 2 and also the finale. Together with last week’s run through of Act 1, this means I’ve now had at least one go at everything I’m involved in. It’s still a fair way off performance standard but still plenty of time until the show.

Give us this day our daily blog

After 10 posts in a row – probably a new blogging record for me – I decided yesterday that the time had come to establish that my new blog is not going to be a daily thing.  I’m still hoping to keep it updated with greater frequency (if not greater regularity) than my previous blogs and I’m certainly enjoying the flexibility and ease-of-use offered by WordPress (and the fact that I can update my blog from my phone as I did on Saturday).