A blog about search, search skills, teaching search, learning how to search, learning how to use Google effectively, learning how to do research. It also covers a good deal of sensemaking and information foraging.
As I wander over hill and through dale, through alpine passes and mountain streams...
A knight striding with flag, bear, and sword. (Bern, Switzerland)
... I'm seeing a kind of exterior artwork on the outside walls of many Swiss buildings. This is such a common thing that surely there must be a specific name for these kinds of paintings that appear on the buildings. Sometimes they're old, sometimes relatively new. Some fancy, but most are stylized in a way that I cannot describe easily--they're often noble, or heroic, frequently bucolic, sometimes civic in design, almost always in a kind of flattened, non-realistic rendering.
The Swiss Mystery for this week is this...
1. Is there a name for this particularly Swiss kind of artwork-on-the-walls? Is there a particular name of the style in which most of them are drawn?
I admit that I do not know the answer yet, but I feel as though there MUST be a rather specific term for these images on the walls of greater Switzerland.
Here are a few examples:
What do you call these? More importantly, what do the LOCALS call this kind of artwork?
I'd like to learn more about this artistic tradition, but don't know quite where to start. Any ideas from the SearchResearch crowd?
When you find the answer(s), let us all know HOW you found them! Let notes in the comments field.
... it's a normal thing to do. But when we're doing online research, it's good to check yourself. This week's Challenge is a little story about why...
My assumption was that these common kitchen appliances had the same mechanism for knowing when the toast / water / rice is at the right temperature or level of doneness.
Then I checked--and had a big surprise. Really?
Today's SearchResearch Challenge is simple:
1. So... how DO each of these devices know when the toast / water / rice is ready?
2. (extra credit) What other devices do you believe you understand, but when you checked, you learned that you actually didn't understand? Does anything spring to mind? Any surprises?
Searching for the answer isn't hard:
[ how does an electric tea kettle know when the water is boiling ]
[ how does a rice cooker know when the rice is done ]
[ how does a toaster know when the toast is done ]
Let's talk about these one-by-one.
Electric tea kettle:Do this query and you'll find a lot of explanatory text telling you that a ring-shaped bimetallic strip changes shape as it warms up, and since it's slightly buckled, when it deforms just enough, it snaps into a different shape, mechanically flipping the heater switch to off when the water hits the boiling point of 100C (212F). Very simple, very clever. But how does it know?
The underside of a tea kettle with the bimetallic ring outlined with a red dashed line.
That bimetallic ring is actually a fairly smart little invention--the tang coming out of the ring lies in the plane of the ring at room temperature, but as the ring starts to bend under the heating of the kettle, it suddenly snaps to a different shape with the tang pointing up. This is called a bistable device, a gizmo that can be in one of two different physical configurations. Of course, the bimetallic strip's clever trick is that it will flip into the "hot" state when the temperature gets high enough, then flip back to the cool state after the heat is off. That rapid flip to the other bistable position is what mechanically flips the power switch back off.
The best example of this I could find is this YouTube short showing a tea kettle thermostat that flips back and forth rapidly when warmed up. (Video link.)
And... I thought that was that.
But as I was writing this up, I ran across a video about electric tea kettles on Steve Mould's YouTube channel that showed me something I'd completely missed: the steam tube!
It turns out (as Steve Mould points out), that the thermostat is actually at the bottom of the tube that is open to the top of the vessel. As the kettle heats up, eventually the steam in the kettle is forced down the tube where it directly heats up the thermostat, which flips at around 95 C (203 F).
Why is this important? Because water boils at different temperatures at different altitudes, so a thermostat that is preset to 100C won't switch off at high altitudes. In Denver, which is at 1609 meters (5280 feet), water boils at 95°C, or 203°F. So if the thermostat only tripped at 100°C, it wouldn't work!
At this point I got really curious about this somewhat sophisticated design, so I looked up a few electric tea kettle patents, where I learned that this is well-known by tea kettle designers. To quote one such patent (US4357520, from 1979): "Alternatively a steam tube or passage, which communicates with a steam or vapour aperture in the upper wall of the container, may be run down the outside of the container. Such a tube or passage may be concealed within or behind a handle structure of the container..."
I thought that was it. NOW I understood how they worked.
But as I was writing this up, on a lark, I searched for:
[ electric tea kettle diagram ]
hoping to find a cross-section of a kettle showing the steam tube.
But NO! I was again surprised to learn that there is a second thermostat, a "boil dry" thermostat that kicks in if/when the first thermostat fails to detect any steam. This would happen if the kettle was switched on without any water. No water, no steam, no steam pressure, no thermostat clicking off.
I found this because I saw this diagram in the search results:
Electric tea kettle circuit diagram. (P/C from Karisimby's blog)
I know enough about electronics to realize that this was NOT what I had in my head. The "steam thermostat" was what I expected. What I did not expect was a second "Boil dry" thermostat.
A bit more searching revealed that such a second thermostat is set at a much higher temperature and is attached directly to the kettle wall. So if the kettle is dry and heating up, the steam thermostat won't kick in, but the boil dry thermostat will open the circuit and stop the heating from running away (and possibly causing a meltdown).
Rice cooker:Again, not a difficult query, but the answer surprised me! I'd assumed that there was a simple bimetallic thermostat in the rice cooker as well--in fact, I'd assumed that it worked in much the same way, probably with an identical part inside.
But I quickly learned that most rice cookers (especially older ones) use a very clever magnet that turns off the heating element when the temperature goes above 100°C, or 223°F.
Basically, there are two heaters in a rice cooker--one that keeps the rice warm and a second heater that boils the water, much like the tea kettle.
However, I learned that rice cookers have a little magnet that holds the switch closed to close the main circuit to the heating element. That circuit heats up the water until it boils, after it boils, the temperature of the magnent will start to rise beyond 100°C, or 223°F. When that happens, the magnet loses it's magnetism, allowing the circuit breaker to pop open, stopping the heating.
The amazing trick here is that the magnet is designed so that it's Curie point (that is, the temperature at which it loses its magnetism) is at 100°C!
The bimetallic strip thermostat works because different metals expand at different rates, causing it to change shape.
I didn't dream that using a magnet's Curie temperature would be used in the simplest of all rice cookers. It's really not obvious that this is would be used to turn off the heat. Incredibly smart use of some sophisticated physics.
Oddly, I can't find any evidence that a rice cooker has a boil dry mechanism! (I assume they do. If you find out, let me know in the comments below.)
To be sure, there are other mechanisms out there for telling when the rice is done--neural fuzzy logic rice cookers with complicated sensing systems. But I love this elegant application of magnets!
Toaster:The big problem with toasters is that there are so many of them. But for the most part, simple toasters are just timing mechanisms... turn the dial, get the level of brown you'd like. It's really up to you learn which dial setting corresponds to the level of toasted that you like.
But there are a LOT of different toasters out there--some with fancy thermocouples to determine temperature, some with just plain old spring-loaded timers that count down the seconds, and some with complex electromagnets to hold down the carriage (that carries the bread/toast on its journey).
The old-fashioned toaster, though, is just a timer... nothing more than that.
Other devices I don't understand?
2. (extra credit) What other devices do you believe you understand, but when you checked, you learned that you actually didn't understand? Does anything spring to mind? Any surprises?
There are LOTS of things I don't understand, but will look into once I get the chance. I want to learn how the magic happens. Among them,
1. iPhone--how it knows how far I've walked or run. I know it counts steps, and I know it has a GPS system in it, so I assume it uses the GPS for distance traveled and counts steps via the on-board accelerometers, but does it combine those information streams in some way? Don't know.
2. Refrigerators--I don't understand the physics of them in detail, but I do know that they have a single cooling unit which then cools the frozen foods at one temperature, but the cool part of the fridge is handled in a different way. Again, how does it know?
The bigger point here is that all of these phenomena are understandable with a little observation and a dash of SRS.
SearchResearch Lessons
1. Expect surprises and be ready for them. Initially I thought that the rice cooker story was going to be straightforward. So it was a surprise when the story got more complicated. I discovered that when I noticed that something I read from the SERP didn't fit in with what I already knew. (And this happened to me twice!)
2. Use multiple document types to get a full perspective. Sometimes a regular web search works just fine, but for complicated searches like the rice cooker, I used Image search, YouTube searches, and even Patent searches to get multiple perspectives. I ALSO looked at multiple sources for each device, partly because some of the documents are simplified versions. (For instance, not all rice cooker stories mention either the steam tube OR the dry boil cutoff thermostat.)
3. Be aware when what you read doesn't match what you think you know. Again, this happens multiple times for every SRS session--I learn things, and then learn something different. When what you read doesn't line up with what you've already read, take that as a signal that there's more to learn!
... in online research is probably that of not checking your assumptions. We tend to see the world without questioning, and we often bake those assumptions into our research behaviors.
Here we see three common, everyday appliances: an electric tea kettle, an ordinary rice cooker, and a plain old toaster.
I've seen these for years--there's nothing especially strange or exotic about them. You've probably used them all as well.
As I was waiting for my toast to turn to a satisfactory shade of brown, I was looking at it standing next to my electric tea kettle, not far from my rice cooker and thinking about how they each know that the toast / water / rice is ready.
My assumption was that they all had the same mechanism for knowing when the toast / water / rice is at the right temperature or level of doneness.
So I was really surprised when I checked my assumption, and found that I was utterly wrong. The only device that I got right was the toaster--I knew that one--the other two surprised me.
Today's SearchResearch Challenge is simple:
1. So... how DO each of these devices know when the toast / water / rice is ready?
2. (extra credit) What other devices do you believe you understand, but when you checked, you learned that you actually didn't understand? Does anything spring to mind? Any surprises?
This SRS Challenge isn't that hard, but it brings up a fairly deep point about when to question our assumptions... and HOW to realize that your assumptions might be wrong. Any ideas?
