NavList:

Regarding the time necessary to calculate the Lunar Distance problem:

I recently had the opportunity, with a sea horizon available, to observe a Moon-Jupiter near limb distance, as well as the requisite altitudes for clearing the distance and calculating the Longitude.

I used Borda's method, which is pure spheical trigonometry, to clear the distance, and the Longitude Time Sight to subsequently calculate the Longitude. All was done as it would have been done in the early 1800's, employing six place logarithmic tables and all corrections applicable per Norie's Tables. The True Distance at Greenwich was taken from currently published 3-hour interval tables and interpolated by proportional logarithms.

The calculation time to complete this work, exclusive of observation time, but including the Longitude work-up was 22-minutes - and I'm a bit rusty. Claims that this problem required hours to solve are simply myths.

When I get the opportunity, it is my intent to publish these observations on the List. However, as the accuracy of Longitude obtained is really astounding, I am double checking everything before giving George and Frank a go at it.

Regards,

Henry