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I see that Excel 2013 has an LN() function available to it...but the flavor of Visual Basic which I have integrated with my graphics program, CorelDraw, does not support this function per se.

I do see that there is a derived function that Corel supports that looks like this:

     Logarithm to base N:

     LogN(X) = Log(X) / Log(N)

I don't (yet) know enough about natural logarithms to know how, if at all, this "LogN()" relates to Excel's "LN()".

Presumably if need be, I could use Excel to generate a list of coordinates where I would want to lay down hash marks for a scale.  But getting Corel to do it directly would be more straightforward...if Corel can do it on its own at all, that is.

I do see that http://www.antiquark.com/sliderule/sim/n3t/virtual-n3-t.html illustrates an Ln scale, and even lets one play around with it.  That will give me an idea of the layout for the scale I should come up with if I can figure out what to feed to an equation to generate it. 

I think before I get into adding a scale to my slide rule, I am going to have to go back to school on logarithms, so to speak.  The last time I worked with them was 45 years ago.

Gary, could you work through one rhumb line problem from beginning to end using your equations, so that I have a model to follow as I try and sort out how to do this myself?  It will help me spot elementary errors if I know what the right answer should be to a particular calculation.

Thanks so much,

Bob