[GreenKeys] a real mechanical analog computer

[Steve Schlink]

Well, since we are already way of topic anyway, for a look at a real analog 
"computer" ...

At least this one has gears, so it has something in common with teletypes.

http://tidesandcurrents.noaa.gov/predma2.html
http://tidesandcurrents.noaa.gov/predmach.html

This machine is now over 100 years old and still functioning, although it 
was electrified (with a sewing machine motor) years ago. It sits in a glass 
enclosure with a push to start button for demonstration in the display area 
of NOAA's headquarters in Silver Spring, MD, about 2 miles north of the DC 
line. I helped with some minor repairs a year or so ago.

There are only 2 or 3 people left around who can set it up, using one well 
guarded book. The twin/spare was scrapped years ago. (What keep that piece 
of junk?) The original is lucky to have survived in that it was moved to 
its present location without any real approval from the basement of the 
Commerce Bldg. in downtown DC.

 From a mathematical formula standpoint,  I suspect that this tide machine 
compared to the trajectory computation of the fire control 
"computers"  would be much more complex and about 50 years earlier.

Steve