My boss is fond of saying, “It isn’t rocket fuel.” Well, this is rocket fuel.
When I was 13 or 14 years old, my brother and I enjoyed building and launching model rockets. My father, the scientist, made rocket fuel for us. I remember him mixing the ingredients in a large pan on the stove.
“Listen,” he said. “This is dangerous. If I tell you to run, then you run. Run out into the orchard and don’t come back to the house until I call you. Understand?”
We nodded and watched. Not long afterwards, Dad became very excited and shouted, “Run! Run!”
Daddy, I’ve just been in a wreck
We got our first snow of the season, a record breaker, with 8 inches in Spokane. April drove home from WSU for the Thanksgiving break. Just outside of Spokane, the road narrowed to one lane due to accidents ahead. Traffic stopped in April’s lane. Unfortunately, the Ford F-350 behind her didn’t stop soon enough!
Highway 195 was closed for two hours later in the evening.
We’re certainly glad to have her home. We’ll be extra nervous when Chris makes the same trip Wednesday night or Thursday morning.
Dirty weblog referrer robot trick
While browsing my web server logs, I noticed something that appears to
be a dirty little trick to drive traffic to other weblogs. I'm getting
hits from a handful of sites that get only the default page (no css,
images, etc.), have referrer fields that point to other weblogs, and
have user agent fields set to
Since many weblogs automatically create a links for referrer they detect, I assume this is just a ploy to get those weblogs to drive a bit of traffic to the offenders sites.
Time to install a bot trap.
First item of Dad’s listed on eBay
Today, I listed the first of many items that belonged to Dad on eBay. This item had no particular sentimental value. It looked like a good candidate for a start. If you're curious, check it out. It is eBay item 2573916471.
Pictures from our Colorado/Arizona trip
With winter here, I'm spending more time indoors, now. Linux gets most of my indoor time. After a long summer of neglecting Linux in favor of bicycling, I've refocused on extending my Linux knowledge and skill.
I've been reading The Art of UNIX Programming by Eric S. Raymond. This isn't the kind of book I would normally purchase. It is virtually devoid of any in-depth technical material, source code listings, and detailed explanation of technique. I spent nearly two hours at Barnes and Noble thumbing through a copy before I decided I had to take it home with me.
I've learned great deal from the book that I wouldn't have gotten from a
more technical treatise. I learned, for example, which IPC mechanisms
are preferred, and that some, although documented, are deprecated and
should not be used. There's a lot of
best practices information to be
gleaned from Eric's new book.
And there were a few threads to chase, as well. Eric referred to Pic as one of his examples of mini-languages. Pic, it turns out, is a tool I immediately put to use. I generated the images in my Vernier scale post a few days ago using Pic.
That lead me on a search for a similar mini-language to use for 3D modeling. I really wanted such a tool when I wrote my Summer Solstice post in June. What I found was POV-ray. POV-ray's scene description language does, indeed, allow me to quickly and easily describe simple models like the one I needed for the Solstice post. It goes far beyond, however. A visit to the POV-ray Hall of Fame (a continuously updated gallery of scenes) is well worth the time.
I bought a used flat bed scanner, an Epson Perfection 1200U, on eBay. When it arrived, I discovered I did not have support compiled into the Linux kernel for USB scanners. Normally, that would be a simple matter of compiling the necessary module and installing it individually. But somewhere along the line, probably with and upgrade to gcc, the 2.4.20 kernel source would no longer compile.
Linux is so stable that there has been no need, whatsoever, for me to keep on top of the kernel releases, recently. So, the need to get the new flatbed scanner working resulted in a download and compile of the 2.4.22 kernel. That was, as always, a trouble free experience. And my sound card now has native kernel support, so I was able to drop the Alsa sound drivers I was using previously.
I'll need some time to experiment with the scanner, but so far, the SANE scanner utilities seem to be doing a perfect job.
Linux certainly hasn't lost it's appeal for me; I'm looking forward to plenty of time with it this winter.
I can remember Dad teaching me how to read a vernier scale, but I never gave much thought, until now, to how and why it works.
The vernier scale is based on some very simple mathematics that yields a surprisingly powerful and useful result.
Consider the following scale. The base scale is on top, the verier scale on the bottom.
Notice that the vernier scale divides 9 units on the base scale into 10 equal parts. Therefore, each vernier unit is 0.9 base units.
1 on the vernier scale falls on a point that must be 0.9 on the base
scale, even though the base scale is not marked at that point. If we
slide the vernier scale 0.1 base units to the right, the
1 on both
scales will align precisely, and the arrow at the origin of the vernier
scale will be positioned precisely at 0.1 base units.
If we slide the vernier scale to the right until the
2 marks on both
scales align, the arrow on the vernier scale will be positioned at 0.2
base units. It must be, because each vernier unit is 0.9 base units; 2
vernier units equal 1.8 base units; 2 – 1.8 = 0.2.
So, as we can see, when a mark on the vernier scale aligns with a mark on the base scale, that mark on the vernier scale indicates, in tenths, where the vernier arrow falls on the base scale.
Take the following setting, for example.
3 on the vernier scale aligns with a mark on the base scale, so
the arrow falls at 2.3 on the base scale.
A common set of vernier calipers allows measurements in thousands of an inch. The base scale is marked inches, and tenths, with each tenth divided into 4 parts (0.025 inches). The vernier scale divides 24 of the smallest marked units on the base scale into 25 vernier units. Each unit on the vernier scale is, therefore 0.024 inches long, 0.001 inches shorter than a unit on the base scale. When a measurement is taken, the thousandths indicated on the vernier scale are added to the nearest 0.025 inch mark on the base scale, left of the vernier origin.
It would be impractical to mark a rule with thousandths of an inch and even more impractical to use, but by employing a vernier scale, measuring that accurately is simple.
The Long Walk
Jenny and I just finished reading The Long Walk by Slavomir Rawicz, the true story of the author's escape from a Siberian prison camp in 1941 and his and his companions three-thousand mile trek, south, through Siberia, the Gobi Desert, Tibet, and over the Himalayas, in winter, to freedom.
The wayfarers suffered days on end without food or water. They pressed on driven only by their sheer will. Slav's story is awe inspiring. I heartily recommend his book.
Jenny and I rarely watch television. Until recently, we spent most of our leisure time cycling. With the loss of Daylight Savings Time, the shorter days, and colder weather, we've been spending more time inside. As an experiment, of sorts, we decided to send some time reading a book together (which means I read aloud and Jenny listens).
It's been an interesting experiment, and I'm ready to find another book to read. We ran across this book at our local Barnes and Noble store. I had actually read about it in the same Rivendell Bicycle Works catalog that lead to the Grandpa's Pine Tar Soap experiment. I guess all things are connected.
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CSS stolen from Tom Coates who didn't even complain.