A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Robin Stuart
Date: 2014 Jun 17, 07:40 -0700
I haven't given a more detailed explanation what appears in my previous posts however I can do it here.
Performing the multiplication cotan(z) = cotan(x) * cos(y) involves aligning the zero pointer on the cosine scale with x on the cotan scale. Then you look for y on the cosine scale and the result z is adjacent on the cotan scale - standard sliderule stuff. If y lies off the cotan scale then, just as with a normal slide rule, you start again and align the zero pointer at the other end and one cycle down on the cosine scale with x on the cotan scale. (Note: the zero pointers are the black triangles. There is one at each end of the cosine scale. Be sure to use the tip of the pointer when aligning numbers on the cotan scale).
Division is also similar to the way it is done with a normal sliderule. To perform the operation cotan(z) = cotan(x) / cos(y) align x on the cotan scale and against y on the cosine scale and read z on the cotan scale using which ever zero pointer is on the cotan scale. Because there is one pointer at each end there is no possibility of run off,
Please let me know if you need more details,