H. O. 9 means Bowditch, a book of nautical tables and information, but in recent years it has been heard of less and less. This shouldn’t be, for in the adoption of short methods first principles are being ignored.
No doubt, there is a need for short methods, although they are nothing more than a re-arrangement of well-known formulas; H. O. 211 being an arrangement of secants and cosecants in substitution for sines and cosines as found in the formula for finding the latitude from a single altitude at a given time. Aquino’s tangent + secant tables are taken from the same formula, and his earlier publication is the well-known cosine-haversine formula with substitutions. These were selected because the formulas are well known to H. 0. 9.
The following short methods from H. 0. 9 are, it is believed, short enough to compete with the new navigation methods.