In ‘The National Maritime Museum’ by Commander W. E. May, R.N. (Vol. VII, p. 336), two lines were transposed in printing. The words ‘thus antedating the invention of Captain K. R. Belch, U.S.N., by many years’ printed on line 39 of p. 337 should come after the words ‘in about 1870’ on line 43, and refer to the double-sextant combined with a station-pointer made by Admiral C. E. Von Pott.