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Electronic Design


They're Knot Fooling Around
I read Bob Pease's article with great interest \["What's All This Knot Stuff, Anyhow? (Part 1)," March 5, p. 142\]. I have always liked a really good knot. Loading the ol' xmas tree on the roof of the '55 Chevy was always a task. Knowing a good knot to hold the lumber from sliding off the roof of the '70 Plymouth was a concern. So I had studied several knots, and used them quite successfully.

One of my coworkers is an Eagle Scout and an active scout leader in Troop 463 in Northford, Conn. He sent me this site on the very subject of knots. In fact, they're animated too:
Bob Daly

As a convinced bowline-tier for close to 50 years, I'm happy to see you give my favorite knot some good words. Apart from its useful features of being both nonslip and easy to undo, the bowline has other virtues.

The strength of a rope is adversely affected by tying knots in it, and the bowline does better than most by maintaining about 85% of the original rope strength. (This was the result of a series of tests made on nylon climbing rope with an engineering-school tensile testing machine, a fine application for this equipment. Note that the result is likely to depend on the construction and material in the rope, because knots tend to damage ropes by "choking" the line, and this will probably be material-dependent.)

But probably the best feature of the bowline is that you can tie it neatly around yourself with just one hand, a trick which is highly recommended to the steeplejack (or mountaineer) who is hanging on grimly with one hand and both feet, while dropped a line from above and asked to tie it around his middle. I've even used this for real a couple of times. If you haven't seen it done, tell me and I'll make a sketch.
Roland Bradbury

I wonder how many other e-mails you have received telling you that the bowline you pictured is not a regular bowline, as the end is outside the loop instead of inside. What you have drawn is often referred to as the ring or stopper bowline. However, as Geoffrey Budworth, IGKT, says, "Knotting ventured, knotting gained."
Harley Babbitz
Manufacturers Rep.

Yeah, a few people told me I had shown the Dutch Bowline, which isn't quite as good as the regular bowline, unless you're Dutch, and then it's better. Thanks for the comments. / rap

Maybe Money Isn't Everything
Regarding "Rich Nations Beat Poor Ones" \[letters column, March 5, p. 66\], that's not always the case. Was Vietnam richer than the U.S.? I don't think so. The U.S. was fighting the wrong war. The people that U.S. soldiers were trying to prop up weren't wanted by the majority of Vietnamese. They couldn't put enough soldiers in the field to defeat the Vietnamese on the ground, and there wasn't enough fuel in the world to defeat them from the air.

Perhaps the nature of anti-aircraft missiles has changed to such an extent that agile fighters, such as the Harrier, which can fly backwards to some extent, are no longer important. But their agility certainly was important to the British victory in the Falkland Islands, as it enabled them to dodge missiles which would otherwise have destroyed them.

The best manuals I have seen in the recent past came from Morphy Richards (breadmaking machine) and Rigaku-Denki (automated crystallographic x-ray spectrometer).

At the height of the "fuel crisis" of the 1970s, my wife and I got lost on the way from Cambridge, England, to Edinburgh, Scotland, at night. We drove to the top of a hill and looked to see if we could see our way better from up there. What we saw astonished us. At a time when our government was imploring us to save energy at all costs, at 3 a.m., as far as the eye could see, it was a sea of light—and bright light. Why didn't we install street lights that come on when something near them moves? The technology is there, and I'm pretty sure it would save its cost in very little time.
A.M. Wooster

A Good Read On TZAs
I just added Bob Pease's excellent article on TZAs to my collection \["What's All This Transimpedance Amplifier Stuff, Anyhow? (Part 1)," Jan. 8, p. 139\]. I also have the Graeme book and a new book by Philip Hobbs, Building Electro-Optical Systems. Have you seen this one? In my opinion, it's very good, and Chapter 18 was one of the most intuitive treatments of TZA tradeoffs and tricks I've seen. I have no connection or stake in it other than the fact that Philip once helped me, gratis via e-mail, with some opto-electronic design problems I had.
John Quinlan

Note Of Appreciation
I wanted to write a lot sooner but did not manage. I wish to express my appreciation over your article "Good Designs Flow From Art, As Well As The Science Of Engineering" \[March 5, p. 156\]. It feels good to read articles like this. I shall preserve it for a long time and show it to people I like.
Sastry Dasigi

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