NavList:

Thanks Greg, enjoyed this one very much.

Apologies for turning up late to the party, did it last week but only now have access to a scanner.

Two sight forms and two Graphics attached. I like much more white space than your index card: it helps to clarify the structure of the task and give room to correct (occasional!) errors on the original.

Otis King is at its proper place in the chart table, so used solar 4 fig calculator for the multiplication in this armchair effort.

Every 4 place Hav/Doniol reduction makes me smile: this one was special for three reasons:

          Having to find the refraction value for 0 altitude -  34.5 ' ... one to remember

          Working a sight with negative Ho and Hc 

          The CTS graphic solution  landed exactly on the first solid line from the origin of Hanno's family of Z curves

Joys of living ... worry not that few of us use Hav/Doniol 4 place. I'm just now reading Everett Rogers 'Diffusion of Innovation' 5th Edition. One of its examples is that of the adoption of citrus fruit juice by the British Merchant Marine to prevent half of ocean going crews being lost to scurvey. Proven to work by a trial on 3 ships, with a control fourth ship that didn't use it, by a Capt Lancaster RN in 1701. Adopted by the British merchant fleet regulator, the 'Board of Trade', in 1865.

Thanks again

Michael Bradley