Le Roi Est Mort

Abstract

Another year thus passed without Vulcan any closer to being confirmed. Eighteen seventy-seven dawned. Once more the world turned its attention to the Paris Observatory. Within its formidable redoubt sat the great mathematician, meditating his stratagems. His resourcefulness had been sorely tested, but he would not be found wanting. Possessed of unusual stubbornness (“increased difficulties ... far from deterring, seemed rather to stimulate him to greater exertions,” as Adams had said), he once more revised his calculations. He decided Vulcan’s failure to appear October 9–10, 1876, was because it moved in a highly eccentric orbit with an extreme inclination he put at 10.9°. He derived a new period: 33 days with the next transit due to occur on March 22, 1877, then not until October 15, 1882.¹ The prospects on the former occasion were uncertain, since his calculations showed the planet’s trajectory would be almost tangent to the limb of the Sun. Clearly, its position could not be calculated with great accuracy.