Portal de Periódicos da CAPES

Australia's earliest planispheres

2003; British Astronomical Association; Volume: 113; Linguagem: Inglês

0007-0297

Wayne Orchiston,

Pacific and Southeast Asian Studies

In 1870, a Sydney-based amateur astronomer named George Butterfield (1841−1910) assembled Australia’s first known planisphere, a description of which was published in the Sydney Mail newspaper: ‘It consists of a sheet of imperial drawing board, on which is drawn a circle of 81⁄2 inches radius, divided into 24 equal parts, and each of these into 60 parts, each 24th part being numbered 12 noon to 12 midnight on one side, and round the other side to 12 noon; the divisions between these hour arcs are marked for every minute, and numbered for every five minutes. ‘Inside this circle, and concentric with it, revolves a circular disc, on which are marked the stars within 33o 51' (the latitude of Sydney) of the South Pole, that point being the axis of the disc, as it is of the apparent motion of the Heavens. On the circumference of the disk are the names and days of each month. Lettered to each fifth day, and marked to each day. ‘... readings are in solar time, which differs from mean or clock time; this difference called the equation of time is indicated by small numbers on an inner circle, showing the number of minutes to be added or subtracted on the day under which the figures are inscribed. ‘... magnitudes of the stars are indicated by the number of radiating petals; of the first magnitude, eight petals; of the second, six petals; stars of the third, fourth, and fifth magnitudes, five, four, and three petals, respectively. ‘There are five stars of the first magnitude; eight of the second; sixteen of the third; twenty-five of the fourth; and eighty-six of the fifth; in all one hundred and fifty, comprising all the stars of those magnitudes in the catalogue of the Royal Astronomical Society, published for the epoch, 1830. ‘Owing to the precession of the equinoxes the positions of the stars are subject to a slight variation. The amount of this recession, though an extremely small quantity annually, by its continual accumulation from year to year, becomes palpable, and the right ascension and declination of the stars for the map is corrected for the present year, 1870.’2 In 1870 September this planisphere was exihibited at the Intercolonial Exhibition in Sydney, where it attracted considerable attention.3 This inspired Butterfield to have it massproduced, and in 1870 November it went on sale at the establishment of F. L. Edwards, a Sydney stationer and amateur astronomer.4 Intended largely for ‘... those engaged in teaching, as well as ... adults who wish on fine evenings to have at Australia’s earliest planispheres