The finished work contained a note to this effect: “The inverse law of gravity holds in all the celestial motions, as was discovered also independently by my countrymen Wren, Hooke, and Halley.”
The book was dedicated to the Royal Society, and to it was prefixed a set of Latin hexameters addressed by Halley to the author, ending with the well known line:
“Nec fac est propius mortali attingere divos.”
(“It is not given to a mortal to get in closer
touch with the gods.”)
Halley was fifty years old when he made his famous prediction of the return of the Comet of 1682. This was in his “Synopsis of Comet Astronomy,” which ended with these words: “Hence I may venture to foretell that this Comet will return again in the year 1758.”
Besides being an astronomer of the first class, Halley was also a good navigator. In 1698 he was commissioned a captain in the Royal Navy and was put in command of the King’s ship, “The Paramour Pink.” With this vessel he set out on a long cruise to the Pacific for the purpose of making observations on the laws which govern magnetic variations. This task he accomplished in a voyage which lasted two years and extended to the fifty-second degree of southern latitude, when the ice compelled him to turn back. On the return voyage his crew mutinied and his lieutenant sided with the mutineers. Halley quelled the mutiny by sheer force of personality, and returning to England got rid of his lieutenant. The results of his voyage were published in his “General Chart of the Variation of the Compass” in 1701. Immediately afterwards Halley set out on another King’s ship and executed by royal command a careful survey of the tides and coasts of the British Channel, an elaborate chart of which he published in 1702.
Next Halley was sent by the King to Dalmatia, for the purpose of selecting and fortifying the port of Trieste.
On Halley’s return to England, he was made Savilian professor of geometry at Oxford, and received an honorary doctor’s degree. He filled two terms of eight years each as secretary to the Royal Society, and early in 1720 he succeeded Flamsteed as Astronomer Royal.
He died on January 14, 1742, at the age of eighty-five in the full possession of his faculties, the foremost astronomer of the day and a man universally beloved and respected. His gravestone stands at the Greenwich Observatory.