On the connexion of the physical sciences / By Mrs. Somerville.

  • Mary Somerville
Date:
1834
Catalogue details

Licence: Public Domain Mark

Credit: On the connexion of the physical sciences / By Mrs. Somerville. Source: Wellcome Collection.

    42/478 page 30
    by the shadow of the planet. The eclipses take place close to the disc of Jupiter when he is near opposition; hut at times the shadow is so projected with regard to the earth, that the third and fourth satellites vanish and reappear on the same side of the disc. These eclipses are in all respects similar to those of the moon; hut, occasionally, the sa- tellites eclipse Jupiter, passing like black spots across his surface, and resemble annular eclipses of the sun. The instant of the beginning or end of an eclipse of a satellite marks the same instant of absolute time to all the inhabitants of the earth; therefore, the time of these eclipses observed by a traveller, when compared with the time of the eclipse computed for Greenwich, or any other fixed meridian, gives the difference of the meridians hi time, and consequently the longitude of the place of observation. It has required all the refinements of modern instruments to render the eclipses of these remote moons available to the mariner ; now, however, that system of bodies invisible to the naked eye, known to man by the aid of science alone, enables him to traverse the ocean, spreading the light of knowledge and the blessings of civi- lization over the most remote regions, and to re- turn loaded with the productions of another hemi- sphere. Nor is this all: the eclipses of Jupiter’s satellites have been the means of a discovery which.
    digitised image 1
    digitised image 2
    digitised image 3