Entry tags:
Home from Pennsic
Left Coopers’ Lake at 1:40 PM yesterday. First stop, pizza in Grove City. Stopped for the night near Delaware Water Gap, which on the way out had been a bit over four hours from home (really bad traffic). Had breakfast at an apparent local favorite spot, then drove home, arriving a little before noon (no significant traffic this time). Backed the trailer into the garage, unloaded the car, unloaded the trailer, re-loaded the trailer with empty chests and things that live there year-round, walked to the farm market for sweet corn, zucchini, etc. D. started a couple of loads of laundry. Retrieved hounds from boarding kennel half a mile away. Took rapid-read Covid tests: both negative.
I managed to get all the way through Pennsic without sunburn, but driving home (even though I was in the driver's seat most of the way, and therefore on the north side of the car) sunburned my hands to the "itchy" level.
At some point during Pennsic, D. picked up a class handout somebody had left behind, on Ptolemaic mathematics, so I read that when I needed a break from unloading and unpacking. Some of it is basic stuff about converting between decimal and sexagesimal, some is standard 9th-grade geometry involving similar triangles, and then they get into spherical geometry, which is much trickier, particularly when trigonometry hasn’t been invented yet. The workhorse tool seems to be something called Menelaus’s Theorem, which specifies a proportion among several arcs in a figure formed by the intersection of four great circles… except it isn’t really a proportion among the arcs, but rather among their chords. And even that isn’t quite right: it’s actually the chords of the double angles of each of these arcs. How did anybody come up with that? I guess the “double angles” part is a transformation between an angle whose vertex is on the opposite side of the sphere and one whose vertex is the center of the sphere, and the “chords” part allows us to work with nice simple planar triangles. Anyway, one can use this theorem to calculate the angle between equator and ecliptic at various times of year (at the equinoxes it’s zero), and thence the positions of sun, moon, and planets.
Then I picked up a book that’s been sitting on the coffee table since Christmas: Seb Falk’s The Light Ages: the Surprising Story of Medieval Science. And a good deal of the first chapter is about the same sort of astronomy: if you live in one place for years, you can observe the northernmost and southernmost places the sun rises and sets, observe the lengths of noonday shadows at various times of the year, and thence derive things like your latitude and the Earth’s axial tilt, which go into the aforementioned Ptolemaic calculations. Of course, everything is much easier if you assume the Earth is a sphere, and its orbit and those of the moon and all the planets are circles. I wonder how much more difficult it would be on a planet with a significantly eccentric orbit. Among other things, the warmest and coldest parts of the year might not correlate closely with the highest and lowest noonday suns, which would change the societal motivation for doing astronomy. And the obvious existence of a non-perfect circle in Creation would have interesting theological implications.
Last Monday we gave a concert in the performing arts tent, entitled “An Evening at the Salle des Ardents: Medieval Smoky Jazz”. All circa-1400 music. There’s a recording, which I need to retrieve from the recorder and edit on the desktop machine before posting it for public consumption. The opening number was a little chaotic, so I may substitute in a recording of it from a rehearsal, but most of the pieces went well and I think are suitable for posting. [Edit: see here. There are a number of wince-worthy moments in the concert, but a bunch of good moments too.]
To do before next Pennsic:
To do in the next week or two:
I managed to get all the way through Pennsic without sunburn, but driving home (even though I was in the driver's seat most of the way, and therefore on the north side of the car) sunburned my hands to the "itchy" level.
At some point during Pennsic, D. picked up a class handout somebody had left behind, on Ptolemaic mathematics, so I read that when I needed a break from unloading and unpacking. Some of it is basic stuff about converting between decimal and sexagesimal, some is standard 9th-grade geometry involving similar triangles, and then they get into spherical geometry, which is much trickier, particularly when trigonometry hasn’t been invented yet. The workhorse tool seems to be something called Menelaus’s Theorem, which specifies a proportion among several arcs in a figure formed by the intersection of four great circles… except it isn’t really a proportion among the arcs, but rather among their chords. And even that isn’t quite right: it’s actually the chords of the double angles of each of these arcs. How did anybody come up with that? I guess the “double angles” part is a transformation between an angle whose vertex is on the opposite side of the sphere and one whose vertex is the center of the sphere, and the “chords” part allows us to work with nice simple planar triangles. Anyway, one can use this theorem to calculate the angle between equator and ecliptic at various times of year (at the equinoxes it’s zero), and thence the positions of sun, moon, and planets.
Then I picked up a book that’s been sitting on the coffee table since Christmas: Seb Falk’s The Light Ages: the Surprising Story of Medieval Science. And a good deal of the first chapter is about the same sort of astronomy: if you live in one place for years, you can observe the northernmost and southernmost places the sun rises and sets, observe the lengths of noonday shadows at various times of the year, and thence derive things like your latitude and the Earth’s axial tilt, which go into the aforementioned Ptolemaic calculations. Of course, everything is much easier if you assume the Earth is a sphere, and its orbit and those of the moon and all the planets are circles. I wonder how much more difficult it would be on a planet with a significantly eccentric orbit. Among other things, the warmest and coldest parts of the year might not correlate closely with the highest and lowest noonday suns, which would change the societal motivation for doing astronomy. And the obvious existence of a non-perfect circle in Creation would have interesting theological implications.
Last Monday we gave a concert in the performing arts tent, entitled “An Evening at the Salle des Ardents: Medieval Smoky Jazz”. All circa-1400 music. There’s a recording, which I need to retrieve from the recorder and edit on the desktop machine before posting it for public consumption. The opening number was a little chaotic, so I may substitute in a recording of it from a rehearsal, but most of the pieces went well and I think are suitable for posting. [Edit: see here. There are a number of wince-worthy moments in the concert, but a bunch of good moments too.]
To do before next Pennsic:
- Buy and/or build a new tent.
Roof panels are largely sewn together, but that's where they've been for several years; no significant progress in Covidtime. Then need to cut and sew together wall pieces, and build or commission poles, and make a bunch of rope attachment points and stake loops, and so on.
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shalmestere points out that we're much more likely to have a new tent by next Pennsic if we order it from a tentsmith. - Finish building new "birdcage" music stand.
Parts are mostly cut out, but they need to be stuck together, and we need an upright and a foot.
- Rebuild cooler chest.
The ends are fine, but the lid and sides are permanently warped, so it never actually closes, which defeats its purpose of hiding a styrofoam cooler; in addition, one of the lid's reinforcing battens which had been loose for years finally fell off completely this Pennsic. Also want to attach handles to the ends, which would make it enormously easier to carry.
- Lose enough belly to fit into my red linen pourpoint.shalmestere has a photo of me in it from eleven years ago today, but when I tried it on at Pennsic, it was nowhere near closing.
- Make more braes and shirts
- Repair existing braes and shirts
- Make more points and aiglets
To do in the next week or two:
- Repair the drinking jug I knocked off the top of the piano while putting away krummhorns from Pennsic ✓
- Wash and put away clothes and dishes from Pennsic ✓
- Put away stuff that was left lying around from Pennsic packing ✓
- Replenish groceries ✓
- Cook normal food ✓
- Edit and post concert audio ✓
- Hem, and attach a linen collar-lining to, the gown that shalmestere made me two weeks ago from one of her old dresses
- Add eyelets to the tailed hose shalmestere made me a few weeks ago
- Finish building the fleece harp-case we started several months ago
- Contact harp-maker to say "yes, we're home from vacation now; feel free to ship the double-strung harp we commissioned two years ago" ✓
- Get Rid Of Stuff
I'd like to set us the challenge that every day we throw/give away one item that's been in our possession, but unused, for years. I figure after a month or two of that, we might notice a difference.