One of the greatest faults with navigators today is their tendency to try to cut down figures in their problems,” says Captain Charles H. Cugle in the preface to his excellent Simple Rules and Problems in Navigation.
Be that as it may, it is fair to presume the Captain did not have Dreinsonstok or Ageton in mind. Moreover, as it is evident that the percentage of error is reduced in proportion to the simplification effected, the navigator who makes use of either or both of the newer methods has a greater advantage against error than is the case with older forms.
“Meridian altitude” is the title for a short and simple form to compute latitude, given to us by Dreisonstok in “H. 0. 208,” but as simple as it is we have to contend with the “human element.” To quote the explanation, “Now, the azimuth is assumed to be 0° or 180° according as the observer faces the elevated pole or has his back to the elevated pole when taking the sight.” Further, "... it has the added advantage of disposing with the necessity of remembering confusing signs.”
It does not, however, entirely eliminate the difficulty of remembering how the result is applied—“away” or “toward.” The question may arise, “Was the elevated pole faced or was the back toward it when the observation was taken?” In practice this is not as easy to answer as it appears, in every case.
The following rule will simplify the application:
Name the HO plus.
Name the HO minus.
Subtract the lesser from the greater, following the form (disregarding sign).
Name the result “a” plus or minus, according to whichever was greater, and apply it to the D. R. (or assumed) latitude in accordance with the sign (add or subtract). For example: “H. 0. 208,” problem 9.
There is but one exception to this When the computed altitude (HO) exceeds 90°, in which case the supplement is used for HO (as instructed “H. O. 20& p. 75), the signs are reversed: the minus and the H0 is plus.