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October 6, 2003
I just read the definition of the telephone in one of your articles and it made me think of something, Why is a microphone called a microphone if its not very small?!?
Good question. The Oxford Universal Dictionary says the word dates back to 1683. Who would have guessed that ? It further says that microphone derives from two Greek words and refers to an instrument used to magnify small sounds. Micro in microphone, therefore, doesn't mean the size of the instrument, rather the ability of that instrument to augment weak sounds. Thanks for the query, best, Tom Farley
October 5, 2003
Not so many dead links
I misread the report I mentioned below. This site now has less than seventy dead links. I've been working hard in the last two days to fix or delete these links, as well as updating information where I can. It's slow work because I want to rewrite so much. Yet, although slightly dated, most pages are still accurate. If I had more time I could explain certain subjects better, but that is an old problem for all writers.
Got my brain scanned this morning. The tech doing my MRI wasn't as cute as the blonde in the photograph below, but things went well enough. (Although I won't know the results for at least a week.) Despite its friendly appearance and high cost, probably a million or more US dollars, there were some odd things about it.
The first surprise was the noise. The tech gave me ear plugs to wear before the test. Good thing. The MRI machine would clunk away for a while, perhaps making adjustments or warming up, and then it wold give out a high pitched scream for 15 to 30 seconds. And it doesn't hum while resting, it makes pulsing sounds, as if it is breathing. Yes, it is claustrophobic, after they send you into the tunnel, but I wasn't too bothered. I kept thinking about a recent hike each time I felt the need to flee. There's a little mirror inside, sort of like a periscope, that gives you a view of the outside world. Didn't help me calm down though because without my glasses I couldn't see more than a foot or two. They should have put HBO on the little screen, that would have helped. How does it work? No idea. But here's a generic explanation from a medical site:
"MRI uses radio frequencies, not X-ray, to obtain signals from various body tissues showing the differences in fluid content. The electromagnetic energy is measured and fed into a computer to form an image that is projected onto a monitor. It's one of the best tests available for a detailed look at certain internal organs and structures of the body."
October 4, 2003
300 dead links?!
Alexa.com offers a good service. Enter your web site address and it will return a report on how many links you have and their status. It seems about 300 of the 1400+ on this site aren't working any more. It's estimated 20% to 30% of the links on the web die every year. It's what's called link rot and one reason I will archive more material from other sites and provide fewer and fewer external links. Fight against this problem by not changing file names. Most files here haven't changed since they were posted. Time to get back to revising pages.
October 3, 2003
Back to work
My left knee was injured while hiking a few weeks ago. I need to stay off my feet for some time so I will concentrate on indoor work instead of my usual outdoor routine. This means working on the website, at least in the mornings, for perhaps the next 10 days. Contact me with any dead links you find or comments you have.
Four Wire
Four wire circuits provides the best quality transmission because transmit and receive paths are separated. Huh? Difficult to explain with words but easy to depict with a photograph, the four wire principle is illustrated with the garishly colored photograph below:
Communicating in the Outback; A Great Read from Down Under
Download this fun Word98 document by clicking here. Four short, detailed pages. From Roger Underwood's book Tree Climber:The Education of a Forester. Used with permission. Roger writes about the primitive but effective telephone systems once used to keep foresters and ordinary people in touch in rural Australia. A great read. You can get the entire book directly from Roger. His e-mail address is yorkgum@git.com.au Australian $28.50 plus postage. That's around $19 American dollars but don't forget that postage! Here's some from the chapter on communicating:
"In this day of the space flight, the direct telecast of Wimbledon, the mobile telephone, email and the FM radio in your car, it takes an effort to remember that only a generation or so ago Western Australian foresters were communicating by mirror."
"All the first lookout towers and forestry stations in WA were equipped with heliographs -- basically a large mirror on a swivel with which competent operators could twinkle a complicated message to each other across the tree-tops. Learning the helio technique and the Morse Code were part of a forester's training in those days. My Uncle Geoff (my mother's brother) was a forester in WA during the late 1920s and 1930s, and had been taught, and become an expert in heliograph communication. . . " Download the .doc
Heliograph example, not part of the book. American forester Harry Gibson flashes messages in 1915 by heliograph in the Wenatchee National Forest.
http://www.lib.duke.edu/forest/
usfscoll/people/Gisborne/Gisborne.html (external link, may be dead)
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Free Telecom Magazines through TradPub.com. Click here to go there
