In 1952 the Institute set up a Working Party, under the chairmanship of Mr. D. H. Sadler, to investigate the accuracy attained in the practice of astronomical navigation at sea. The report that follows was presented in summary to the Technical Committee on 15 February, 1957, and formed the subject of a discussion at the Institute's meeting on 21 June.

The following conclusions relate to a total of 424c, observations received by the Working Party from 173 observers, and are representative of navigational practice as a whole only in so far as the observations, and the observers, are so representative. Only 3319 observations from 1 r6 observers were retained as suitable for analysis, and in nearly half of these observations the ship's position is not known sufficiently accurately for them to be included in the main analysis.