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Thanks Dave -  an interesting post - it reminds me of the single straight line 'haversine nomogram' method on page 168 of 'Heavenly Mathematics'

So. thanks again to both yourself and Greg. 

The search is over, at least for me. I'd misremembered the name of the author - it was Goodwin, in 1905 - I've attached the file. I still can't remember where I first came across it. I like it because it's the earliest reference I've found making clear the all round simplification of astro by using haversine only in all sight reductions. Nobody took a much notice of Goodwin then, as far as you can tell from the post 1905 textbooks. Yet another example of the very slow diffusion of improved  technologies. 

All the best

Michael