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    Re: Calculator v. Slide Rule for Ex-Meridian Correction
    From: Francis Upchurch
    Date: 2016 Jan 7, 09:33 -0800

    Suggestions for cel nav linear slide rule.

    I guess one advantage of the linear is the sheer number of scales you can add. 

    On my cylindrical  Fuller, I only need the outer cylinder ( ? equivalent to A/B) and the sin scale (have added cosines in red travelling the other way). I do not need logs/log-logs etc. I can do any cel nav and nav calculations with these 3 scales.

    Perhaps the proposed linear could just have A/B ,C/D , no logs or log logs, but perhaps "stretch" the sines and cosines ( and Tan or cotan if you want to use the Bygrave formula as per Gary's suggestion) over several scales to reduce compression and increase accuracy?

    Also, one of the great advantages of the modern cheap calculator are the memories. So you can stowe an angle such as LHA, Dec, Latitude, and for the cosine formula and lunars where you use these numbers  repeatedly, either cos or sin, speeds things up immensly and reduces input keying errors. 

    Could you do this with a slide rule by having a "Degrees" scale and then separate sin/cos? You could then mark the said angle with erasable marker pen (i.e stowe it in the  memory) and line this up immediately with the sin or cosine as required?

    Just a thought.


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