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my text woven in below...

glapook@pacbell.net schrieb:
> You're close to the original Bygave which has a cotan scale 8.8 meters
> long. But you would have to adjust your spacing slightly because there
> can only be 44 turns between 20' and 89�40' since each turn must equal
> a change in log cotan of .1. The log cotan of 89� 40' is about  -2.2
> and the log cotan of 20' is about 2.2, a range of 4.4 making  44
> changes of .1 which is the reason for the 44 turns on the original
> Bygrave. 

I did't get that.
Do you mean, there is some restrictin in the spacing - that one turn on 
the scale has to have a certain interval (0.1) covered?

I thought I'm free to choose whatever diameter I like and that the 
scales length divided by the circumference gives the approximate number 
of turns. Why 44, then?

Or do you just talk about the original dimensions?

> Its tube is 2.5 inches in diameter 

Well, 2 inches was just an example...
I took it, because anything between 40 and 50mm diameter handles well, 
haptically.

> times Pi makes the
> circumfance of 7.85 inches times 44 turns equals 345.58 inches or 8.77
> meters. If you adjust the spacing but keep the pitch unchanged and
> make 56 turns it would cover a range of 1'30 to 89� 40' and so
> eliminate the problem of sun sights near the equinoxes.
> 

How so? By prolonging the scale down to values below the original
0� 20'? Twelve turns for 19 minutes of arc?

Regards,
	Thomas.



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