Six’s Thermometer. The Maximum Minimum.

max min thermometer

Better known as the maximum minimum thermometer, my first, a now defunct mercury version was purchased some 20 years ago. And though I’ve only ever owned three two of these in my life, alas, I’ve had to buy a new one. It’s very old school. But I like that, old school. Like the day I bought Loaded by The Velvet Underground. On vinyl.

Back on planet earth, Sweet Jane still humming in my ears…. I’ve written about James Six’s 1782 invention here before for other reasons, but it is such a legendary piece of equipment for any plants person or parent. So good, when wee Ella first went down to her own room at around 3 months of age, I placed it on her bedroom wall. Smart Dad ? I thought so.

In Short What Does A Max Min Thermometer Do ?

It records, lets say overnight, the lowest and highest temperatures simultaneously, whilst at the same time telling you the current temperature.

How The Flip Does It Manage That ?

Imagine if you will any old school thermometer which used to use mercury. Now add in a 2nd column, side by side; one of them works backwards so to speak, recording the lowest temperature and the other the highest. As it gets warm one rises and as it gets cold the other falls. Very simple. Except, they’ve popped a wee widget in the top both columns.

So lets say temps reach a high of 18 celsius and then drop that evening to say 5 degrees C…  the wee widget thingys stays behind at whatever the highest and also the lowest was. Simples.

What’s The Use Of The Max Min To A Gardener ?

I’ll keep this hypothetical example as basic as I possibly can. For the moment, lets say you come out one morning and your seedlings are just dead. There are two immediate [in this example] possibilities.

  1. Your seedlings [in short] fried in the heat during the evening sun
  2. There was an unannounced overnight drop in temperatures, below zero and your seedlings died in the cold

The answer is similar symptoms and two possibilities, a little like under and overwatering plants if you will. Except here, one checks the max min thermometer. No sub-zero temperatures – well then it must be the other. Case closed. And as noted before, as a horticulturist sometimes I cannot prevent things from going wrong, hard as I may try, I can only explain why. And before some smarty pants notes it, I am aware the cause may also have been damping off.

max min seperation

Problems You May Have:

  • It happens regular that the columns separate. 99% of the time this can be solved by swinging it centrifugally at arm’s length whilst holding the reset centre button.
  • To prevent incorrect readings – Keep it in the shade and avoid sources of heat.
  • Also: I tried the digital one. But in short, it was rubbish and broke. And then you realise, that although the invention itself may have evolved [the use of mercury is banned in EU countries] slightly. In reality it hasn’t changed at all.

In Picture:

  • above top is my newest mercury free thermometer
  • Pictured middle is my 20 year old mercury version
  • below in a wheel barrow like a shovel that’s allergic to soil is my digital thermometer, that doesn’t like getting wet

Of note: James Six‘ story. A real tale of rags to riches, in a sense. Also, he invented it in 1782. Seventeen. Eighty. Two. When you think about it, the dude was a flippin genius.

digital max min thermometer

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