Monday, May 26, 2008

Wooly metaphors in seventeenth century science

I have a 2000 word essay to write about Descartes, which is one reason I haven't written anything here recently.

While researching it, I discovered that Pascal carried out experiments on a variety of things, including wine and wool. That led me into checking up about wool and experiments in the seventeenth century, and it seemed that wool - by which they meant fleece - was a useful metaphor for air. They were investigating about air pressure. We are used to thinking about air as having weight, but in the seventeenth century this was a matter of debate.

Torricelli compared a column of air to a cylinder filled by wool. When a weight is placed on the top, the wool is compressed. He said that if a knife was thrust through the cylinder, the wool-pressure is unchanged. Pascal pointed out that the weight of the wool itself compresses the wool at the bottom of the heap.

Boyle used the analogy in a different way, referring to wool that was being compressed. He states "upon the removal of the external pressure, by opening the hand more or less, the compressed wool doth, as it were, spontaneously expand ... till the fleece hath either regained its former dimensions", or at least as close to its dimensions as the "compressing hand... will permit".

Descartes too used a wooly analogy, but unfortunately his was wrong. Asked why mecury did not flow out of an inverted tube, he said that the air was like wool and "the ether in its pores to be like whirlwinds moving about in the wool." Everything was moving in a circle: there couldn't be a vacuum at the top, because Descartes thought vacuums were impossible.

Wednesday, May 14, 2008

Knitters versus the BBC

Or maybe that should be the BBC versus knitters.

If you hang around the same knitting groups I do, you'll have come across this Angel Knits thread, and this Ravelry one.

And now even the BBC itself is posting about it.

The BBC article does seem really quite fair from my understanding of the story: it refers to the "unscrupulous" other people who were using Mazzam's patterns. (I think their legal team have checked it very throughly.)

The essence of the story is that Mazzam created a pattern for knitted Adipose babies from the first episode of the current season of Dr Who and posted it on her website. Then someone started selling copies of the pattern on ebay, and I think Mazzam complained to ebay and the patterns were removed. After that the BBC got in touch with Mazzam etc etc. My guess is the ebay seller shopped her to the BBC, but who knows?

FWIW, the nice thing about Dr Who is that I always see the latest episode within 24 hours of its' first showing. I never need to worry about spoilers on the net, unlike almost every other sci-fi program I watch.

Thursday, May 08, 2008

very large spiders

I'm not normally a person who gets scared of spiders. However when I saw an enormous one [1] in the basin before I had my coffee, I couldn't help but let out a little screech.
(All pictures clickable, but you might not want to look.)

It took about an hour until I was brave enough to deal with her, with a plastic cup and a piece of junk mail.
spider under cup

After I took the cup off her, she paused as if to pose for photographs.
freed spiderspider, close-up under cup

Then suddenly she scuttled in the direction of the open front door...
spider scuttling

... but instead scooted behind a flowerpot and off into the shrubs.
dark behind flowerpot

[1] That's enormous spider for England, not enormous spider for places like Australia.