CHAP. xm.

NEPTUNE.

83

Mr. Lassell’s satellite revolves round the primary at a dis-tance about equal to that of the Moon from the Earth , andshines with the brightness of a star of the 14th magnitude.

Shortly after the discovery of Neptune , it was found that ithad been seen on two occasions, in 1795, by Lalande, whoseobservations have materially assisted astronomers in obtaininga more correct determination of the planet’s orbit than theywould otherwise have been able to have done, if they had beencompelled to depend on modem observations only.

Owing to its immense distance the inhabitants of Neptune can only see the planets Saturn and Uranus , but none of theplanets which revolve within the orbit of the former. Thoughdeprived of a view of the principal members of the solar sys-tem, the Neptunian astronomers are well circumstanced forinspecting comets, and are also able to take, probably withconsiderable success, observations on stellar parallax, seeingthey are in possession of a base line of 5,700,000,000 miles,or 30 times the length of that to which we are confined.