CompuServe Thread

#Inappropriate language

2 messages in this thread
#23055From: Jack CrenshawNov 29, 1989 10:46 PM
No, what I meant was: that convention center is very near the area of greatest damage in the last quake. BTW, I've been meaning to report to the folks over on CLM: The quake was detected by our inertial lab tiltmeters here in Clearwater, Fla. Remember, these are not seismometers, but part of our lab equipment. The instruments show a tilt of about +/- 3 arc seconds, lasting over a period of about 1.5 hours (the waves disperse as they travel). Took about 30 minutes for the first waves to arrive. If I do come to the conference, I'll bring a copy of the graph. These guys give a measure of an arc-second. Take a perfectly level board 17 feet long. Pick up one end, and lay a human hair under it. It's now tilted by one arc-sec. The graphs would seem to imply that these meters can easily detect angles on the order of 0.1 arc-sec or so.
#23081From: John M. DlugoszDec 1, 1989 12:31 AM
Interesting, all right. Tell me, what kind of pinball machine is that that it yells "tilt" with such a small push? Really, what kind of equiptment needs a tiltmeter that fine? A friend of mine (just finished up at Texas A&M) built a laser. He set up a sand-table and soon had a working inferometer in the bedroom. He could detect a train passing through Bryon, and footsteps on the walkway outside, and trucks driving by, etc. He also set up a target so that a small object (like a hair) placed in the beam would difract the light and you could read the thinkness of the object off the chart. He could measure the thinkness of a hair so well as to distinguish between individuals. The chart was marked in nanometers! He also folded up his brother in the sofabed to see if such a thing was possible. Such is the mind of a scientist.