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Harri,

I've just built a simple prototype using your graphs. It only took about 20 minutes to make (takes days to make a slide rule) and much to my utter amazement, it seems to work!

See attached pics. It is just 2 paper copies of the dot graph baseplate stuck to either side of a plywood sheet. then rotors made from transparency film side  A and B. Attached at pivot point with drawing pins. Obviously, this is only for "proof of princiople" test drive. I shall eventyually build a more robust version using acrylic sheets for the rotors. I don't know if you would be able to add the verniers and other extras from the Luykx paper? If so, I will wait for that before starting.

I tested the prototype using the example in Luykx. See pics. It Works well, even though slightly smaller (Xand Y axis just over 7.5 inches , whereas I think the original is 10 inches.) also no vernier which might make it more accurate.

Either way, it is incredibly easy and quick. I got Hc in under a minute. Faster than Bygrave or even calculator.

Cannot understand why this did not "take off" to excuse my pun!

It is so easy to build and use, I would be interested to hear what Gary thinks?

Thanks again Harri for the graphs.

Best wishes

Francis

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