DISCOVERY FROM PREDICTION.

Pelorus Guardian and Miners' Advocate., Volume 17, Issue 7, 27 January 1903, Page 2

DISCOVERY FROM PREDICTION.

FINDING THE PLANET NEPTUNE. It was in the year 1846, that two distinguished men—Professor Adams in Cambridge, and M. Leverrier, in Paris —independently of each other and at the same time, set out, so to speak, upon the hunt for an unknown planet. Unknown it most assuredly was, and yet of its existence they were absolutely certain. The explanation of this certainty of theirs is extremely simple. It is a matter of common knowledge that the planets travel round the sun, and that one of the things that helps to keep each planet in its own particular path is the force called gravitation—the force of attraction • which exists between the planet and any other external body. Now, knowing the position, path, velocity, and other circumstances of a given planet at a given time, the astronomer can easily predict the position of that planet at a future time. It is a mere matter of arithmetic. Thus do our almanacks tell us. the exact time of the next eclipse of the sun or the next full moon. But in the year 1795, there happened to be what the astronomers called a “ discrepancy ” in the position of the planet Uranus, that is to say its observed position did not coincide exactly with its position as predicted by exact calculation. The only thing that could account for this discrepancy was the influence of some unknown body which had not entered into the calculations of the astronomers, but it was not until 1846 that the two above-mentioned scientists proceeded to calculate the exact position of path of this unknown body which was disturbing the known planet Uranus. Very soon after Leverrier had shown where this unknown body was to be found, it was found by Do Galle, of Berlin, in almost the identical spot predicted. It is now known as the planet Neptune.