There are people who go gaga over gadgets, and then there are skeptical folks like me. If I buy gadget it really has to promise to do something I need it to do. (Case in point: I still don’t own an i-anything. No iPhone, no iPad, not even–gasp!–an iPod.)

But the gadgets in the garden that I really enjoy having are my two maximum-minimum thermometers. Imagine a device that tells you how hot and cold it got anywhere in your garden over whatever time period you like.

I have one in the greenhouse, where it tells me how hot the temperature got inside while I was at work. This is information you won’t get from a weather report.

You could also use a pair of them to identify microclimates around your yard and to answer specific questions like, Is the lower part of a slope more liable to get frost than the top? Or, how much temperature difference is there between the beds on the north and south sides of the house?

The versions I have are totally analog devices where the mercury in the thermometer pushes up a little piece of metal inside the glass column on both the warm and cold sides. To reset the thing you pull the metal pieces down from the outside using a magnet. Primitive, but effective, as befitting a device that was invented in 1782 by James Six.

Yes, I did say that the thermometers are filled with mercury. Mine are over twenty years old. Regulations in many places today would stipulate that the fluid be something more environmentally responsible, but the devices would function the same way. You can also get these in digital versions, as well as those that have a dial instead of fluid-filled glass chambers. (I generally find dial thermometers to be less accurate in general, however.)

There you have it. My favorite boring little device. You can’t use them to surf the web or make gelato. But then what use does a plant have with Hulu or Facebook?