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Wednesday! Hump day! The middle of the week!
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Man, last night I got so much done, though! I'd been putting off several chores, and I did them all, so that's good.
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I noticed that when I have to soak the output port, the water where I add the epsom salts gets cold.
Last night I was thinking about it, and using nothing but the Laws of Thermodynamics I figured out why it was happening. I felt so smart.
1) Magnesium sulfate is a crystal at room temperature. That means that there are basically energy "holes" into which the atoms fall to form the crystal; if you wish to disturb this crystalline structure, you must put energy into it to force the atoms out of their "holes". If this wasn't the case, it wouldn't be a crystal; it'd probably be liquid at room temperature. The crystalline structure represents the minimum energy of the system and you have to put energy in to disturb it.
2) The crystals are approximately room temperature (70°) before they go into the bath water. The bath water is over 90° (probably closer to 95°). Adding the crystals to the water increases the mass of the water; at the same time you're dumping a "cold reservoir" into a "hot reservoir" and the temperatures must equalize.
So the salt pulls heat out of the water as it dissolves, but the total energy remains the same.
Besides, adding the salt to the water changes its properties. Salt water (a solution of sodium chloride, I mean) has--for example--a different freezing point than pure water. It also changes the specific heat capacity of the water. These effects are nontrivial.
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Turns out that the neighbor--the one the cop was asking about the other day--was down in Arkansas taking care of his sister. He only got back yesterday and we chatted a little bit last night.
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The snow is melting. Every year I think about charging up the batteries for my remote control truck, and then running it around on the frozen crust you get when snow partly thaws and refreezes--and every year I don't get around to it. *sigh*
The truck is vintage 1988. I bought it from Radio Shack when I was working at Software Yutzetera; it was a Christmas present for myself. It's true 4WD and it has two gear ranges (high and low) and in low it can crawl through just about anything. Grass is no problem.
But I have this idea about putting it into "high" and running it around on the frozen crusty snow, and doing donuts and stuff. I think it'd be fun.
Just, apparently, not fun enough actually to do it.
In 1992, I worked out how to mount my video camera to it. I'd bought an 8mm RCA camcorder in May of that year, and I discovered that it was light enough to mount to the truck. I borrowed the mounting screw from a tripod and drilled an appropriately-sized hole in the roof of the truck body; the camcorder was then screwed to the roof of the truck. It worked! It was stable! The truck (in low) had the guts to drag the camera around with ease!
I could even run the truck in high gear on a sufficiently hard surface, like concrete. No problem. I never did much with this, but I have some video of my experiments with it.
Years later I happened to see some wildlife show where the camera crew was trying to get a camera into a lion's den. So they mounted a camera to an RC truck chassis, covered the whole thing with fur to make it look like a lion cub, and drove it up to the lion...and the sound of the truck was suspiciously familiar: it sounded exactly like my RC truck from Radio Shack.
(The lion, however, was fooled well enough to take the thing into her den, exactly as the camera crew had hoped.)
These days, of course, you can buy a tiny digital video camera the size of a pack of gum, and it won't cost you much to boot; there's no challenge to mounting something like that to an RC vehicle. *sigh*
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In Expanded Universe Heinlein talked about how he and his wife spent weeks calculating and plotting an orbit on a roll of butcher paper for the sake of two sentences in his novel Space Cadet.
He said: "A young astronomer asked me, 'Why didn't you just run it through a computer?'
"'My dear boy--' I don't often call PhDs in hard sciences 'my dear boy'; they impress me-- 'My dear boy, this was 1947.'"
Someday, one of my nieces or nephews is going to ask me that kind of question. "Why didn't you just...?" And my reply is going to be just about as condescending as Heinlein's was; I won't be able to help myself.
Hell, half the time I catch myself asking, "Why didn't I just...?" Then I have to condescend to myself, which is no mean feat. I'm pretty sure the Catholic church frowns upon that kind of thing, for one.
"Couldn't I have looked that up on-line? OF COURSE NOT, DOOFUS! THAT WAS 1987! AL GORE HADN'T INVENTED THE INTERNET YET!"
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Man, the liberal lefty gloating is just oozing from this AP story about Borders filing for bankruptcy.
"Bookseller Borders, which helped pioneer superstores that put countless mom-and-pop bookshops out of business, filed for bankruptcy protection Wednesday, sunk by crushing debt and sluggishness in adapting to a rapidly changing industry." "Sluggishness in adapting to a rapidly changing industry"? Oh, you mean, like the "mom-and-pop bookshops" had?
I wonder if the store near here will be one of the 200 which are closed? For me, it'll just mean ordering my manga instead of going to the store and buying it.
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BTW, I know I've been poor-mouthing a lot, but I think I can spare the $8 or so for volume 7 of Kimi ni Todoke. That's not going to break the bank or anything; if it does, the bank is already broke.
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You know, I've been going to bed pretty consistently around 10 o'clock. Pity it's AM....