NavList:

Frank, back in March 2006 there was a discussion on this list regarding the 1897 workbook calculations from Charles W. Morgan. One thing that wasn't addressed then (as far as I can see) is how the navigator got the local apparent time from the sum of logarithms. To me it seems that table V in Bowditch (1851 or 1880 editions) was used to reduce the declination from the NA, first to local apparent noon and as a second step to the local time of the time sight. But in those editions of Bowditch there is no table of log sine square of half angle (or log haversine) so if you used Bowditch you had to divide the sum of logs by two before entering the log sine table and then you could readily read the local apparent time, am as well as pm. And I don't see this division by two anywhere. I don't think that the division was done mentally, as otherwise very simple steps like adding 90° to the declination in order to get polar distance were carefully noted on the paper. Do you know if some other table of log trig functions were available onboard?
Lars