Downstream — Trip 3

On the previous trip I walked from Oxford to Shillingford on the Thames Path, and on this trip I was planning to walk to Pangbourne. Getting to Shillingford requires a bit of planning as the buses aren't terribly frequent, so I got up early (07:00 on a Saturday!) for a 08:50 bus from Reading to Shillingford to continue downstream on my adventure.

Day 5 — Shillingford to Reading

Downstream — Day 5

Setting off from Shillingford I quickly came upon the river Thames again, where I was sharing the path with a (very slow) running group—I was keeping up while walking! The first activity on the river itself came at Benson Marina where early birds where getting their canoes in the water, avoiding a range of other motorised pleasure craft.

Wallingford wasn't very far away, and it is a quite picturesque old market town. The Thames Path doesn't go through the town itself, but I did catch some of it on the bus on the way to the start of this walk, and when returning from Shillingford on my previous walk.

Five kilometres beyond Wallingford the Thames Path dives under the Moulsford Railway Bridge before the path diverges from the river around a school. It was an unpleasant section up a hill, and then along a busy and narrow road before the path moves back towards the river, where it joins the tow path by going through a pub's garden. I hope that in the future this diversion would not be needed.

This walk featured six locks, from Benson Lock near the start, to Caversham Lock near Reading. I noticed that although the locks themselves are not getting much larger, the accompanying weirs most definitely do. I spent a little time at Goring Lock just before lunch.

I walked into the small village of Goring-on-Thames to have lunch in a "locals" pub where I had my first first-hand "Brexit Experience". I think I'll leave that story for a separate post though.

After lunch I walked back to the river, and noticed that the landscape was very different from most of the other landscapes along the Thames so far. Instead of it being flat, and wide open, near Goring, the landscape suddenly turned very hilly around me. I did some googling and found that this specific feature is called the Goring Gap. Apparently, about a hundred thousand years ago the Thames didn't flow through Oxford and London but instead went through St. Albans and Ipswitch. During the last ice age the route got diverted because there was a glacier in the way. The Goring Gap is the new route that the Thames cut out through the hills.

The feature became even more apparent when the Thames Path diverted slightly from the river and had me going right up a hill. Near the top I spoke with some other hikers which assured me this was the only location where the Thames Path would do that.

My original plan was to finish at Pangbourne, but it was still early and the weather was nice, so I decided to continue to Reading, with its much easier rail connections.

At Purley the path left the Thames for a while, as due to "access rights" the path can't follow the river closely. Annoyingly that meant up another bit of uphill. Although it wasn't particularly a long stretch, it was quite steep. When I got back to the river, a rain (drizzle) shower started, which kept showing its head all the way back to my finish in Reading.

The last three kilometres go past the normally quiet fields of Little John's farm, but with the Reading Festival only a week away, it was a busy business of setting up for the festival.

Just before Reading I crossed under the Caversham bridge, the last bridge on this part of the walk. Before boarding my train in Reading, I had a well deserved pint at The Three Guineas right in front of the station. Another 34km done!

Photos from my Adventure on the Thames Path are available on Flickr, and all videos on Vimeo. You can also see all the photos on a map.


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Downstream — Trip 2

It had been a few weeks since the previous walk. It had been quite hot and therefore I left it a little to continue along the Thames Path. Today was a lot cooler to start with, with some scattered showers predicted. As this was another weekend day I suspected rail engineering works—and indeed, there were no trains from Paddington to Oxford. The rail replacement bus which took me from Didcot Parkway towards the start in Oxford was luckily will organised, and I only ended up being about 15 minutes later than I originally had hoped for.

Day 4 — Oxford to Shillingford

Downstream — Day 4

It was fairly windy, and a little chilly when I left Oxford along the river. There were lots of rowers out on the Thames, which didn't come as a big surprise as that's what Oxford's stretch on the Thames Isis is known for. Not only were there lots of rowing clubs out, but also plenty of amateurs.

After a while it started to become darker and darker, and I started to wonder whether I was going to keep it dry. I encountered a pair of hikers also doing the Thames Path having a break near one of the boat houses. After having a chat, and avoiding a tree branch being blown out of the tree, I decided to continue and mentioned that I would chance getting rained upon. Without surprise, 5 minutes later it was pelting it down. I found some shelter under a few trees to put on my rain coat, but by the time I managed to put on my coat it was already dry. The additional humidity wasn't that great though.

Just before Abingdon, and its lock, there is a complicated section on the Thames Path that isn't very well signed. OpenStreetMap has the Thames Path (near) perfectly mapped, so it was easy enough for me to find the route, but I did assist somebody going in the opposite direction and explained where she had to go.

In Abingdon I had lunch at the Nag's Head, which is situated on its own island, Nag's Head Island. I opted for a traditional fish & chips, and had a pint of the local brew, called Nag's Island. Just when I was finishing lunch it started to drizzle a little bit, but it had already stopped by the time I had finished my visit to the little coder's room.

Unfortunately the drizzle did come back a few times over the next hours, while I was getting closer to the big towers of the Didcot power stations, which were looming on the horizon. Just before Culham I stopped to have a look at the Swift Ditch, and old short cut for the river Thames ignoring Abingdon. It is no longer in use, and very overgrown, but it was the fastest route for nearly a thousand years.

During the next bit of the walk, there were a great many locks to go past and over, until I came upon the river Thame. From the source at Thames' Head to where the river Thames meats the river Thame, the Thames is also called the Isis. Especially in Oxford do make a big deal out of that. On some Ordnance Survey maps you will still see "River Thames or Isis" for the whole stretch from the source to the Thame.

About 20 minutes later I arrived at my finish today at Shillingford, where I took the bus into Reading, via a bus-replacement bus in Wallingford, and via Henley-on-Thames as the schedule worked better for that. Why wait 30 minutes for a fast route that gets me into Reading 3 minutes earlier while it was very clearly going to rain soon? In Reading, the trains into London were unsurprisingly delayed, as they are so often.

Photos from my Adventure on the Thames Path are available on Flickr, and all videos on Vimeo. You can also see all the photos on a map.


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Downstream — Trip 1

As you might have picked up on, I am walking the whole length of the Thames Path currently. All 184 miles from the source to the Thames Barrier.

I started making videos about each day of walking, which I will be posting here, but the videos don't tell the whole story so I have decided to write about it as well. This is the story of my first trip, which I did over 3 days at the end of June. I had taken the Monday off so that I could to the first 3 stages in one go. That's mostly necessary because there is no, or really crappy, public transport along this first third of the Thames Path. But both the source, and Oxford, are reasonably easy to do by train.

Day 1 — Source to Cricklade

Downstream — Day 1

The first day started by getting the train to Kemble, which is about a mile away from the source in the Cotswolds. After being delayed in Paddington for an hour, the change at Swindon wasn't great either, as the smaller train into Kemble was very full as the previous London to Swindon train had been cancelled. Getting from Kemble station to the source was a little bit tricky, as it wasn't overly well sign posted. And once you get in the fields near the source, you basically have to have a compass to follow it, as there is no hint of the river yet at all.

When I made it to the source, I rested for a bit before starting my walk along "the river" towards Cricklade. The first bit was really just walking in a field, to a little past where I got onto the path from Kemble, where there was suddenly a little stream, with really clear water. From there on, the river gradually became wider and wider. Most of this first day was easy to walk, with mostly paths, and even though I thought I'd see a lot of mud, there was basically none. It having been so warm in the last few weeks really helped.

I was also quite excited when I spotted the first wild life. At first I thought it was a snake, but it turned out to be a fake-snake, a Slow-worm. We have them in the Netherlands too. Not much after that, I also spotted a single pheasant.

Walking through the Cotswolds Water Park with its many lakes was quite variable. Some were quiet and had waterbirds, others were loud with people attempting to waterski.

Just before Cricklade I walked through the North Meadow, with its abundance of wild plants. Apparently it's one of the very few real meadows left in the UK.

Once I made it to Cricklade, I checked in into the White Hart Hotel, had a shower, and promptly mapped the whole town on OpenStreetMap. Then it was time for a pint, and dinner. While checking in my pint on Untappd I noticed that there was a nearby venue, The Red Lion, which also features its own brews. I spend most of the rest of the evening there trying out their brews in the nicely cool garden reading a book (and twitter!). It was a good end of the day after a 22km walk.

Day 2 — Cricklade to Newbridge

Downstream — Day 2

I got up really early (7:30am!!) to have breakfast and to head out as early as I could. I had to cover a lot of ground today to make it to Newbridge where I had booked a night to stay in an inn. I knew it was a long way, and unfortunately I had developed a blister on my heel. Luckily I had packed blister plasters so this didn't end up too big of a deal. Sunday morning in Cricklade was really quiet, with only a few people walking their dogs. It is not a big town, and soon I found myself in the country side.

Just before Lechlade, my Thames Path in the Country guide said that there was an annoying section along the A361, quite a bit away from the river. But since the guide was written, the Thames Path had been redirected through a path much closer to the river after having secured access. This new section had lots of brand new gates, and would surely have been a big improvement if there weren't a few fields of stinging nettles to get through. Walking in shorts was not a clever plan there.

I came upon the first swans, boats, and of course, the first lock (St. John's Lock). I spend a little time here, as locks always fascinated me. But as I had a long walk today, I didn't linger too long.

I had lunch at Ye Olde Swan. I thought their web site had said they brewed their own beer, but that appeared to be not really true. I still had lunch with a lovely pint on their outdoor Thames-overlooking terrace.

After lunch many of the "paths" turned into fields of plants that I had to battle through for a while, and many had nettles. Where the path was a bit easier, there were lots of butterflies and dragonflies. I probably brought a little bit too little water, but found out that most locks will have a water point. That was particularly useful on this hot section later in the day.

At about 19:00, I made it to the end of the section at Newbridge. I would be staying at The Rose Revived.

Day 3 — Newbridge to Oxford

Downstream — Day 3

After a good night's rest I left rather early again. Not quite because I had a long way to go (only 22km!), but mostly so that I could take it very slowly. The previous day's walk had definitely taken its toll.

The Thames Path went straight through the pub's garden, so I didn't have very far to the path. Once I got out of the garden, there were very many rabbits hopping around, only to be disturbed by me, one fellow hiker, and a very adventurous farmer which found it necessary to mow the hay at 08:30 in the morning, on a Sunday.

After having to go around a caravan park bordering the river, and through fields of sheep, I made good progress. With the river a bit wider, there was quite a lot more boat traffic on the Thames, and even some people swimming in it. I guess the Thames is quite a bit cleaner before cities like Oxford, Reading, and London dump their waste in it.

After about half way, I ran into a sign saying that one of the bridges over one of the tributaries was closed and that I should take a detour instead. That detour was very poorly signed, but with some help of the well mapped paths on OpenStreetMap, I found myself a new route. About a third through the detour, on the top of a hill, I ran into another hiker which informed me that the bridge wasn't actually closed. Which stinks, as this meant that I didn't actually walk the whole Thames Path, even though it was about the same distance.

After passing the Godstow Abbey Ruins, near Oxford, the river side became busy with people (and geese!) that were enjoying the river on this hot day. I was happy to be done with the walking around 15:00, and refresh myself with a pint and lunch before heading home by train to London.

Photos from my Adventure on the Thames Path are available on Flickr, and all videos on Vimeo. You can also see all the photos on a map.


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Downstream — Day 1

I have started walking the whole length of the Thames Path. 184 miles from the source to the Thames Barrier. While walking it, I'm making a little documentary, "Downstream", of which the first episode is here:

Downstream — Day 1

It's my first ever attempt at doing something like this, and hence, very rough. It covers the first day out of a three day long walking trip, and I will be adding further episodes of this segments, and then further walking trips in the future.



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Last week I listened to an episode of The Sceptics' Guide to the Universe where the word of the week was "analemma". An analemma is a diagram showing the position of the Sun in the sky over the course of a year, as viewed at a fixed time of day from the same location on Earth. I once tried to make such a diagram when I was still living in Norway from a series of photos, but the weather wasn't consistent enough to make that work.

But as I am currently starting to update the Guide to Date and Time Programming for a second edition, I was wondering whether I could create an analemma from existing PHP functions. Unfortunately, PHP only provides functionality to calculate when the Sun is at its highest point, through date_sun_info():

$sunInfo = date_sun_info(
        (new DateTimeImmutable())->getTimestamp(), // Unix timestamp
        51.53,                                     // latitude
        -0.19                                      // longitude

$zenith = new DateTimeImmutable( "@{$sunInfo['transit']}" );
echo $zenith->format( DateTimeImmutable::ISO8601 ), "\n";

Which on February 26th, was at 2018-02-26T12:13:38+0000 in London.

Then I remembered that a few years ago I wrote Where is the Sun?. There I features a new hobby library "astro" that I was working on. This library implements a few astronomical calculations. I wrote a little PHP extension around it too: php-solarsystem. Neither library or extension have really been released.

The php-solarsystem extension implements just one function: earth_sunpos(), which fortunately does exactly what I needed for drawing an analemma: it gives you the position of the Sun in the sky for a specific location on Earth at a specific time.

With this function, all I had to do is calculate the position of the Sun in the sky at the same time-of-day for a whole year. With the DatePeriod class in PHP, I can easily create an iterator that does just that:

date_default_timezone_set( "UTC" );

$dateStart = new DateTimeImmutable( "2018-01-01 09:00" );
$dateEnd   = $dateStart->modify( "+1 year 1 day" );
$dateInterval = new DateInterval( "P1D" );

foreach ( new DatePeriod( $dateStart, $dateInterval, $dateEnd ) as $date )

We don't really want Daylight Saving Time to be in the way, so we set the time zone to just UTC, which works fine for London for which we'll draw the analemma.

We start at the start of the year (2018-01-01 09:00) and iterate for a year and a day (+1 year 1 day) so we can create a closed loop. Each iteration increases the returned DateTimeImmutable by exactly one day (P1D).

After defining the latitude and longitude of London, all we need to do is to use the earth_sunpos() function to calculate the azimuth and altitude inside the loop. Azimuth is the direction of where the Sun is, with 180° being due South. And altitude is the height of the Sun above the horizon.

$lat = 51.53;
$lon = -0.09;

foreach ( new DatePeriod( $dateStart, $dateInterval, $dateEnd ) as $date )
        $ts = $date->format( 'U' );
        $position = earth_sunpos( $ts, $lat, $lon );
        echo $ts, "\n";
        echo $position['azimuth'], ",";
        echo $position['altitude'], "\n";

The script outputs the calculation as a "CSV", which we should redirect to a file:

php tests/analemma.php > /tmp/analemma.csv

To plot we use the following gnuplot script:

set style line 1 lt 1 lw 2 pt 0 ps 0 linecolor rgb "orange"
set style line 2 lt 1 lw 1 pt 0 ps 0 linecolor rgb "grey"

set datafile separator comma
set xrange [100:150]
set yrange [0:50]

set grid linestyle 2
set terminal png size 640,640 enhanced font "Helvetica,12"
set output '/tmp/analemma.png'

plot "/tmp/analemma.csv" using 2:3 title "London @ 9 am" with linespoints linestyle 1

With this script, we can then draw the analemma:

gnuplot /tmp/analemma.plot

The result:


Analemma (Plot) — Derick Rethans


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