The journal of Thomas Maclear containing frequent observations of the phenomena of Jupiter; lunar occultations of stars and planets; observations of lunar and solar eclipses, sunspots, Mars and meteors; records of thermometer and barometer readings; and general remarks on the weather. There are observations of Halley's Comet for September 1835 to March 1836, with many pen and ink sketches and notes on the appearance and growth of the tail. There are also references to Encke's Comet and an earthquake shock, as well as to an error in the 'Nautical Almanac' for 1835. Much of latter part of the journal is comprised of observations and notes relating to the triangulation of features in the countryside around the Cape Observatory and the determination of the longitude of Simon's Bay. This material includes references to Charles Piazzi Smyth and Sir John Herschel, and to the instruments used, which included the 14-foot reflector, Jones' 5-foot achromatic, the 46-inch achromatic, the mural circle and the repeating circle and theodolite, as well as the following time-keepers: Hardy's Clock, Arnold's ½ second chronometer number 326 and the Perrington chronometers numbers 171 and 2183.