Photography ... astronomy ... art ... design ... technology
(... and the odd rant)

All of these make my world go 'round, to some extent, and they will all be found here at some time or other. Some of the photography can be purchased from my Redbubble site. I can also be found at Tempus Fugit (no longer being updated).

Tuesday, October 23, 2007

The tangled web

Dictionaries & the WWW: I love how you can go looking for one thing, and end up somewhere totally different, if you're of a mind to follow the path. It kind of fits in with the sentiment that we should "chase wild geese - that's what they're for."

This evening, I went looking for the history behind the ISO 'A' format paper sizes, following a discussion with a local artist today. I felt it was probably had some ancient British or German origin, which just happened to translate to the strange 297x210mm for A4 (etc). Turns out it is connected with old German & French thoughts on the merit of a format in which the ratio of the 2 sides of the sheet is 1:[square root of 2]. This allows a sheet to be folded in 2, and still be the same shape. Markus Kuhn says this:

"One of the oldest written records regarding the sqrt(2) aspect ratio for paper sizes is a letter that the physics professor Georg Christoph Lichtenberg (University of Göttingen, Germany, 1742-1799) wrote 1786-10-25 to Johann Beckmann. In it, Lichtenberg explains the practical and aesthetic advantages of the sqrt(2) aspect ratio, and of his discovery that paper with that aspect ratio was commonly available at the time. (There are also suggestions that the task to find a paper format that is similar to itself after being cut in half appeared as a question in mathematics exams as early as 1755.)"

However, James wondered how they arrived at an odd number like 297mm, which doesn't multiply to a nice round number. The answer is simple, and logical - from a metric viewpoint: A0 is one square metre, or very nearly so (with the 1:[square root of 2] ratio). Everything follows from there. Here endeth the lesson.

The point of this is that, having gone in search of old technology, I stumbled across someting very much of the present, a Flash animation. The front page of this site has a mesmeric animated mandala, and the succeeding page has an equally fascinating linear array. Both are affected by movement of the cursor with the the bounds of the graphic. Have a go:


Anonymous said...

Duncan, not entirely sure that

"or very nearly so"

satisfies me!


Duncan said...

James, I'm as disappointed as you; in my book, one square metre is 1x10^6 sq mm, but A0 is just 997920 sq mm, which is a significant shortfall. One square metre would require 1189x841, instead of 1188x840 mm. As you suggest, it's clearly unsatisfactory. What shall we do about it...?

Anonymous said...

we must write to someone and get it fixed ...

those missing mm keep me awake at night ...