Horologium, the Clock, is north of Hydra, and south of Eridanus. Three of its stars, α, δ, and ψ, at the extreme northern end of the constellation, seem to be referred to by Al-Sufi in his description of Eridanus, but he does not give their exact positions. Most of the stars forming this constellation were below Al-Sufi’s horizon.
Reticulum, the Net, is a small constellation to the east of Hydrus and Horologium. The brightest star of the constellation is α (3·36 Harvard, 3·3 Cordoba, and “coloured”).
Dorado, the Sword Fish, lies east of Reticulum and west of Pictor. It contains only two stars brighter than the 4th magnitude. These are α (3·47 Harvard) and β (3·81 Harvard, but suspected of variation). About 3° east of α Reticuli is the variable star R Doradus. It varies from 4·8 to 6·8, and its period is about 345 days. Gould calls it “excessively red.” It may be followed through all its fluctuations of light with an opera-glass.
Mensa, or Mons Mensa, the Table Mountain, lies between Dorado and the South Pole, and represents the Table Mountain of the Cape of Good Hope. It contains no star brighter than the 5th magnitude.
Pictor, the Painter’s Easel, lies north of Doradus, and south of Columba. It contains no very bright stars, the brightest being α (3·30 Harvard).
Volans, the Flying Fish, is north of Mensa, and south and west of Argo. Its brighter stars, with the exception of α and β, form an irregular six-sided figure. Its brightest star is β (3·65) according to the Harvard measures. The Cordoba estimates, however, range from 3·6 to 4·4, and Gould says its colour is “bright yellow.” Williams rated it 3·8.
Chamælion.—This small constellation lies south of Volans, and north of Mensa and Octans. None of its stars are brighter than the 4th magnitude, its brightest being α (4·08 Harvard) and γ (4·10).
Argo.—This large constellation extends much further south than Al-Sufi could follow it. The most southern star he mentions is ε Carinæ, but south of this are several bright stars. β Carinæ is 1·80 according to the Harvard measures; υ Carinæ, 3·08; θ, 3·03; ω, 3·56; and others. A little north-west of ι is the long-period variable R Carinæ (9h 29m·7, S. 62° 21′, 1900). It varies from 4·5 at maximum to 10 at minimum, and the period is about 309·7 days. A little east of R Carinæ is another remarkable variable star, l Carinæ (R.A. 9h 42m·5, S. 62° 3′). It varies from 3·6 to 5·0 magnitude, with a period of 35½ days from maximum to maximum. All the light changes can be observed with an opera-glass, or even with the naked eye. It was discovered at Cordoba. The spectrum is of the solar type (G).
Musca, the Bee, is a small constellation south of the Southern Cross and Centaurus. Its brightest stars are α (2·84 Harvard) and β (3·26). These two stars form a fine pair south of α Crucis. Closely south-east of α is the short-period variable R Muscæ. It varies from 6·5 to 7·6 magnitude, and its period is about 19 hours. All its changes of light may be observed with a good opera-glass.
Apus, the Bird of Paradise, lies south-east of Musca, and north of Octans. Its brightest star is α, about the 4th magnitude. Williams calls it “deep yellow.” About 3° north-west of α, in the direction of the Southern Cross, is θ Apodis, which was found to be variable at Cordoba from 5½ to 6½. The spectrum is of the third type, which includes so many variable stars.