NavList:

John Karl, you wrote:
"However, it will take some effort to compare the calculation of the rising time of the pole to the fairly-easy star-star clearing calculation. In fact, even the constraint on the coordinates of stars to be capable of being at the same azimuth is a little demanding.
Add this to its limitation on sight timing, It seems to me that the Ellenborough method doesn't offer much advantage in today's age of calculators."

Oh absolutely that's true. The Ellenborough method was an interesting historical curiosity. If it had been genuinely effective, it would have lasted. One advantage to bear in mind is that navigators, both historically and today, don't like holding their sextants at strange angles. It can be physically uncomfortable, and it just doesn't "seem right" to many people. That's a significant advantage of keeping the sights in a vertical circle. The other "significant advantage" depends on the student. Some people will find the idea of simply subtracting/adding the standard altitude corrections very obvious and intuitive. That shouldn't be ignored. If they get it, they'll do it.

By the way, you speak of "today's age of calculators"... You mean the 1970s?? ;-)

One nice way to use something like Ellenborough's approach to the star-star problem, if not the actual calculations, would be to set up a little software application that provides a set of convenient opportunities for vertically aligned stars at various distances during some pre-determined period of time. For example, you might ask it to give good choices for every thirty degrees from 30 to 120 during the next three hours. Or you might ask it to limit the selection to twilight. You could have it flash a display of a star map with a blinking arc during the appropriate time period. It could be quite entertaining. And in parallel with "if they get it, they'll do it" I would add, "if they're entertained, they'll do it".

-FER

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