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Adventure of a Thermohygrograph: The Adventure Begins!

Thermohygrograph TraceThere are some things to note: For one thing, a thermohygrograph is a chart recorder which makes a graph of changing temperature and relative-humidity. For another thing, Zyra moving house is not a simple matter of upping-sticks and setting up somewhere else next week. The fact is that there are several 40ft shipping containers to move, and these take a time to fill up with the carefully-catalogued stuff. So, as Container 1 had the caravan packed into it, it had Thermohygrograph 1 packed into a box inside the caravan, which itself was at the toe-end of the container. Therefore, it has not been seen for a while, and there has been no chance to change the chart paper!

Meanwhile Thermohygrograph 2 remained at home until Container 2 was acquired, and then the thermohygrograph was placed in a box and hung up near the doors of the container, just inside, right up at the top, near one of the air vents. It was decided that this would be much easier for monitoring changing humidity, and also for changing the chart paper.

It's also worth knowing that thermohygrographs are precision instruments which are usually used in carefully controlled environments such as museums, where it's important that the temperature and humidity remain about the same. But what happens when a thermohygrograph is put inside a 40ft shipping container and left there for over a month. Well, some interesting results occur...Thermohygrograph Trace

This trace starts on the 15th of November 2009, during which time Thermohygrograph 2 was in a house in Lincolnshire, UK. Not a well-heated house, but certainly kept warm by judicious use of burning gambling machines to save money. On this trace, the full length of the chart represents 31 days. You can see on the trace, the first few nights and days, and a moderately stable environment. The bottom trace in red is the temperature in degrees Celsius, and the top trace in black is the Relative Humidity in % (percent). The daily trend of up and down temperature and humidity was measured for a few days, until the 20th of November, when the thermohygrograph was put in a storage unit (a numbered cardboard box with vents) in transported by van to another town, where the shipping containers were being stored.

You can see on the trace, there's a smudge where the travelling occurred, and then the thermohygrograph finds itself in a new environment. You can see the sudden change is quite marked, as the environment inside a metal shipping container at a depot is considerably more subject to changes from night to day. That first night in the container, the temperature plummeted and the relative humidity soared, and a daily pattern of changes continued.

Please note that although the horizontal axis records time, you should disregard the Monday, Tuesday, Wednesday etc in this case, as the thermohygrograph was set to record 31 days per chart, not 7. The Casella de-luxe version incorporates a fine clock mechanism that has dip-switches which can be set to record 1 day, 7 days, or 31 days. The vertical axis is more important, and it's worth noting that the pens do not actually move "up and down" but more along an arc. However, they share an axis in common. There's also an offset in time, which is so the pens avoid collision with each-other.

The first trace, as seen in-situ on the machine, forms the first part of the second trace. At that point you can see the smudge, and after that, the environment recorded is drastically different.

Here's the trace...

Thermohygrograph Trace

Another thing about this is the fact that the containers were outdoors in the worst winter for 30 years, and there was one day when the temperature was 22 degrees C at one point in the day, and then at night it fell to zero. The freezing weather, with snow and ice, continued, and with the pen charting temperature in red, with the pen tracking along the zero line, eventually the pen came off!

The humidity continued to be recorded and went through wild swings up and down, and the chart ends somewhere in the middle.

At that point, which was the 13th of January 2010, the thermohygrograph was attended to, a new piece of chart paper put in, and the temperature pen fitted back on the bar again.

It is a dramatic chart of thermohygrography, with drastic changes recorded. And this is before the voyage across the sea begins. These readings were all taken in a container in a storage depot. In effect these are night and day conditions inside a container in winter in the UK!

There may be some more test runs like this, with a few more helpful links to Casella or www.casellacel.com , and some more offbeat charts, but this is all leading up to The Voyage, in which Zyra's house contents are shipped from the UK to Panama, and the hope is that the thermohygrographs in the shipping containers will monitor transatlantic freight conditions.

Update: The Voyage. See The Voyage of a Thermohygrograph. This includes some transatlantic thermohygrography, as the temperature and humidity are more-or-less recorded on a chart.