Dijkstra's Beard

The story is of how Edsger Dijkstra and Jaap Zonneveld agreed to stop shaving until they had completed the implementation of X-1 Algol compiler is well documented.  However, their underlying reason for doing so is not quite as well known.  Here Dijkstra himself explains it in a letter addressed to Maarten van Emden:

We were to implement with five of us: Aad van Wijngaarden, Jaap Zonneveld, Joke Feringa, Freek Barning, and myself.  Feringa and Barning left quite soon.  Van Wijngaarden did not contribute — on the contrary! — but pretended otherwise to the outside world. I had been warned by Bram Loopstra and Carel Scholten [hardware designers formerly at the Mathematical Centre] that the little chief was not adverse to showing off other peoples’ work as his own.  I was not in the mood to let that happen to me.  At that time Jaap, van W. and I were clean-shaven; Jaap had a moustache.  To make clear that the two of us were doing the work, Jaap and I decided not to shave until the implementation worked, being convinced that van W. would not follow us in this.  In this way we made it clear who was responsible for the Algol compiler.  Thus it happened; that was around Pentecost [a European holiday six weeks after Easter].  In August the system worked.  Jaap got rid of his moustache and beard soon after; I retained them.

So the beards were their way of making sure that their boss didn't cheat them out of the credit for writing the the compiler!

For those who are interested, a description and listing of the Dijkstra-Zonnefeld compiler can be found here:  F.E.J. Kruseman Aretz, The Dijkstra–Zonneveld ALGOL 60 compiler for the Electrologica X1, Note SEN-N0301 June 30, 2003

Using Wget to Download a Web-Site

This evening I wanted to download the Blender Python API documentation onto my  laptop so I could refer to it when I am not connected to the web. I knew that I could use the Linux command line program Wget to do this but it took me quite a bit of experimenting to get the right options.  Initially I was just using the -r and -k options but Wget would go off and download pages from other web-sites.  Eventually I discovered the -L option which restricts download to pages that are linked relative to the initial page.  This did the job:

wget -rkL http://www.blender.org/documentation/245PythonDoc/frames.html

This left a directory structure named www.blender.org in my home directory and this structure contained correctly interlinked copies of the pages I needed. For more details on the Wget options see the Wget man page.

Tick

This afternoon I discovered this gorged tick on my stomach.  It was about 3mm long. Ticks are arachnids, not insects, but I have no idea what sort of tick it is.  The web doesn't seem to offer much help in classifying them.

I am a bit uncertain as to where and when I could have picked it up.  I haven't been rolling in any grass, or been near any cats or dogs for weeks.  I did go up Reading University grounds yesterday but the only thing I did that could have possibly allowed a parasite to get onto me was brush past some tree branches.  Maybe some tick eggs have been lying dormant a long while in my clothing or my bed and are just starting to hatch out.  I did put the heating on last night, for the first time in ages.  I think I will wash all my bed sheets, just to be on the safe side. I have also looked up the symptoms of Lyme disease, the most serious disease transmitted by ticks, just in case.

The Razors and Tweezers Culture

From a comment by Martin Rundkvist at Aardvarchaeology:

Just look at Late Bronze Age graves. Full of razors and tweezers, of all the bizarre things they could have chosen. And those things are hallmarks of their culture. People are strange.

Update on Sat 2008-07-05 by Tristram Brelstaff

After my recent experience with a tick, I have to say that I now understand why some people might hold razors and tweezers in high esteem.

My Walking Speed

Yesterday I discovered that I walk at a speed of around 100 metres per minute. 

Zoe had asked me how far I walked each day so I was trying to measure my walk to the station on a map.  For some reason I chose to measure it in kilometres rather than miles, as I normally would, and the resulting 2.4 km rang a bell: it takes me about 24 minutes to cover that distance each morning - an average speed of 100 metres per minute.  As a check I measured the other end of my daily journey, from Farnborough North to Frimley, with a similar result: 2.3 km, and that takes me about 23 minutes.  Again 100 metres per minute.

I wish I had known this when I was younger.  Being able to accurately estimate how long it would take me to walk somewhere could have saved me a lot of time when added up over the years.  Also, it would have been cool to be able to accurately estimate distances just from how long it took me to walk them.