A annotated copy of Porter's script for 'The Night Sky in February' on the disappearance of Venus as an evening star and its reappearance as a morning star, Jupiter rising at midnight near Spica, and Saturn and Mars in the sunrise; Mars to be at opposition in November, the plotting of planetary positions, and the 'Nautical Almanac' and the tables of Simon Newcomb and George Hill; the advent of electronic machines for calculations of these ephemerides; the high degree of accuracy of the tables required for comparison with observations given that time is now available to a 1000th of a second; older theories of planetary motion being badly in need of revision, with this being done in the U.S.A.; and the method of calculation, firstly for the five outer planets, and then the four inner ones, by a general theory giving new tables to allow for the errors becoming noticeable.