The publication of the paper Astro-fix by Computation by Oliver C. Collins in the April number of the Journal serves as a reminder that the observation for the determination of the latitude from two altitudes, usually known as the double altitude problem, is one of some celebrity in the history of navigation.

The following notes on the subject may be of some interest although they are far from complete, having been compiled from such books as happened to be readily available, and can only be considered as an introduction to the subject.