A copy of Porter's script for 'The Night Sky in August' on statistical methods in astronomy; the Plough and the movement of Arcturus over 1,800 years since the time of Ptolemy, which Edmond Halley called attention to in 1718; the proper motions of stars, including Arcturus, Sirius and Procyon, analysed statistically by William Herschel, giving similar results to modern measurements; stellar velocities determined by spectroscopic analysis, the velocities increasing towards the galactic centre; revolution about the galactic centre and variations of the movements, with star clusters such as the Pleiades and Hyades moving together; Sirius and the Plough also being part of a local cluster; and radio telescopes receiving signals from the centre of the galaxy.