| Year of Comet |
Node | Perihelion | Inclination | Distance |
| 1531 | 49° | 301° | 18° | 0·57 |
| 1607 | 50° | 302° | 17° | 0·59 |
| 1682 | 51° | 302° | 18° | 0·58 |
The figures are not quite the same, but they are so nearly the same that if we tried to draw the three orbits we should find the pencil going over the same line as nearly as possible: and Halley immediately said that instead of three separate comets, the same one must have come three times, in the same path, which it took about seventy-six years to go round. The path must, therefore, not be a parabola, which does not admit of return, but a long ellipse. And the comet would continue to pay us visits every seventy-six years, the next visit being due in 1758. He knew that he would be dead then, but he hoped that when his words came true, the world would remember to credit an Englishman with the prophecy. Here are his actual Latin words—in those days scientific papers, intended to be read by the whole world, were written in Latin—a language all nations knew, though they might not know the language of their next neighbours.
Quocirca si secundum predicta nostra redierit iterum circa annum 1758, hoc primum ab homine Anglo inventum fuisse non inficiabitur æqua posteritas.
He was proud of his achievement, not for himself but for his nation; and that national pride is appreciated not only by us, but by other countries. My
