I hope all of you celebrated Pi day on Saturday. Mind you unlike most holidays Pi day uses the US dating style. In the US you write dates Month/Day/Year, whereas nearly everywhere else in the world writes it Day/Month/Year. Pi day would be on the 31st of April, but there isn’t one so in this case we go with the US convention. And in answer to your question, yes, this is confusing. Half the people up here write dates in the US style and half in the British. If someone writes 3/3/15 I don’t know if they mean the third of March or…, OK well maybe that isn’t a good example. Anyway, I just avoid the whole issue by writing 14/March/15 on all of my documents at work. Even when that isn’t the date, I just write the same thing, 14/March/15, on every document and let the chips fall where they may. It was really confusing a couple of years ago.

Anyway, Pi day was on Saturday. Actually this was the Grand Unified Pi Day. It was 3/14/15, which as I’m sure all of you know is the longer version of Pi. If you wanted to be exceptionally geeky you could have toasted Pi at 3/14/15 9:26:57, but that’s a bit too much for even us. 

Now Pi Day isn’t the only special day for the Physics crowd. 
There’s February the sixth, Avogadro’s Day that celebrates Avogadro’s Number, 6.02x10e23, the number of atoms in a Mole of anything.
There’s April seventh, Hubble’s Day that celebrates Hubble’s Constant, the speed which galaxies are receding from each other, 70.4 km/sec/megaparsec.
There’s the twenty ninth of May, Bohr Day that celebrates Bohr’s Radius, the distance between the proton and electron in the Hydrogen atom, 5.29x10e-11meters.
And of course there’s April second, Planck’s Day that celebrates Planck’s Constant, 2x4.

Last week we included a picture of the new landscaping on the end of the house. I almost said North side or East side, or South side, but then I realized this isn't Minnesota. Here things are parallel to the ocean, not compass directions. The island and therefore the beach and therefore our street and therefore our house is turned at an odd angle to the rest of the world and we can't really say The North Side. Also we're farther North than those of you in the US so depending on time of year, the sun can rise and set along about two thirds of the horizon so we’re not really sure about East or West either. We really never know what direction is what. If someone asks which way we're facing we just say, “You, we're facing you".

One thing that we didn’t expect was how many people were surprised that we made the large leaf stepping stones ourselves. They’re really not that hard. As to how, well therein lies a story. You see we'd wanted to make these stepping stones ever since we were in Minnesota. Marsha had seen them somewhere and we really wanted to try it. Fortunately we did not make them in Minnesota, as we would have wanted to bring them with us and they’re really heavy. But now that we are living in The Last House We Will Ever Own we felt that we could make them, put them down, and that would be that. 

To make the stones you will need
Water
Concrete. We used bags of Quickrete from Home Depot. I think it was called Patio Mix or something like that. It has the gravel in it already so all you need to add is the aforementioned water. 
Heavy plastic sheeting. This is to put under the leaves to keep the concrete off of whatever is underneath, grass gravel, whatever.
A nasty, ratty ugly wheelbarrow or bucket. The wheelbarrow is better because it’s easier to stir than a bucket. It’s also on wheels so you won’t need to carry the mixture to where you are casting the leaves. Ratty and ugly? Well it will be when you’re done, especially if you don’t wash it out really well. Might as well start with it in that shape if you can.
Some concrete wire. Some of the online instructions say chicken wire. Real concrete mesh is heavier gauge and the mesh is smaller than chickenwire. That makes it, and your stepping stones much stronger.
Rubber gloves. Concrete, actually any lime based material, plaster, spackle, concrete, etc, is very hard on your skin. It's also abrasive so light rubber gloves will shred quickly. Get some good heavy duty rubber gloves. 
Rhubarb leaves. We had some huge ones, nearly a yard across. They made huge stones, and each one took a full bag of concrete. Next time we might go with smaller leaves.
Concrete dye. They have dye that you can mix into your concrete to make it a more pleasing colour than the normal grey. Who knew?  Anyway we got a tan colour that makes the stones look like sandstone. The bottle looked red, but the stones came out a nice yellow tan. 
Oh and wear grungy clothes. This will be hard dirty work and you don't want to have anything on that you give a damn about. 

So to start put the bag of concrete in the wheelbarrow. Start adding water and mixing as you go. You can use a shovel or such to mix but I found that to work out the lumps and to get a really complete mix you needed to get your hands into it. I do the same when I’m making cookies. Always mix wet into the dry, and not the other way. If you start with the water you’ll find it really hard to control the mixture. On the bag it’ll say how much water to add. Put in about 2/3 of that and mix. Then add more until you get the right consistency. You don’t want it as runny as the stuff that comes out of a cement truck. That’ll flow over the sides of the leaf and make a mess. On the other hand you don’t want it to be too dry and stiff or it won’t get as hard as you might want. Kinda like pudding is about right. While you’re mixing, add the concrete colour so it gets mixed in thoroughly.

Lay the plastic sheeting out. For a 3 foot leaf something like 4x5 would be enough. You just want a margin around the leaf. 

Lay the leaf in the middle of the plastic sheeting. Make sure the underside where all the nice veins are is facing up so the concrete can flow into the shapes.

Cut a piece of your concrete mesh wire to fit the leaf. Keep the edge of the wire an inch or two inside the edge of the leaf. This is to make sure all the nasty wire ends are buried inside the concrete and not sticking out where they’ll snag on your bare foot. Form the wire with your hands so it’s flat. You don’t want it trying to curl up while the concrete is drying. 

Pour about an inch of concrete mix onto the leaf. Spread it out with your hands or a trowel. You want to cover right up to but not beyond the edge of the leaf. 

Lay the concrete mesh wire onto the concrete. Wiggle it a bit to make sure it’s seated into the concrete.

Pour another inch of concrete on top of the leaf. Form the edge of the concrete so it’s smooth and follows the outline of the leaf. 

Lay another sheet of plastic on top of your stepping stone. This is to keep it from drying out too fast. 

Repeat with the rest of your stones.

When you’re done walk away. Wash everything up and go have a beer, you earned it. Don’t mess with the stones for a while. Concrete will “dry” in a day or two but it takes much longer for it to cure, and it won’t be full strength until it cures. You made the stones in the middle of the driveway so nobody can get out of the garage? Oh, that’s too bad. For a week or so, each day go out and wet down the stones with a hose to keep them from drying too fast. After a week or two they should be mostly cured (we waited two years, just to be sure). Flip the stones over, scrub off the remains of the leaf off to show the nice leaf patio stone. Now that the stones are good and hard you can place it where you want. Oh, you made them in the back yard and need them a few hundred meters away in the front? Shoulda’ thought about that before you started.

PIX: First I was working with the graphics program GIMP this week and discovered something weird. Second, here is a nice sunrise I caught at work.