The establishment of a system of magnetic observatories in various parts of British territory all over the globe was accomplished mainly on his representations; and a great part of his life was devoted to their direction, and to the reduction and discussion of the observations.
The establishment, in 1671 and 1676 respectively, of the French and English national observatories at once typified and stimulated progress.
Further, we know that in the 8th century B.C., there were observatories in most of the large cities in the valley of the Euphrates, and that professional astronomers regularly took observations of the heavens, copies of which were sent to the king of Assyria; and from a cuneiform inscription found in the palace of Sennacherib at Nineveh, the text of which is given by George Smith,5 we learn that at that time the epochs of eclipses of both sun and moon were predicted as possible - probably by means of the cycle of 223 lunations or Chaldaean Saros - and that observations were made accordingly.
Leverrier placed it on a totally new footing, freed it from the control of the Bureau of Longitudes, and raised it to its due rank among the observatories of Europe.
A type of instrument which has sufficient sensibility to record the various phases of unfelt earthquake motion, and which, at the suggestion of a committee of the British Association, has been adopted at many observatories throughout the world, is shown in fig.
For descriptions of the arrangements adopted in some observatories see the following: U.S. observatories, Terrestrial Magnetism, 1903, 8, i 1 Utrecht, Terrestrial Magnetism, 1900, 5, 49; St Maur, Terrestrial Magnetism, 1898, 3, I Potsdam, Ver'offentlichungen des k.
The instruments and methods thus due to him are substantially those employed in the magnetic observatories throughout the world.
Eighteen observatories scattered north and south of the equator divided the sky among them; and the outcome of their combined operations aimed at the production of a catalogue of at least 2,000,000 strictly determined stars, together with a colossal map in 22,000 sheets, showing stars to the fourteenth magnitude, in numbers difficult to estimate.
The method of measuring the horizontal component which is almost exclusively used, both in fixed observatories and in the field, consists in observing the period of a freely suspended magnet, and then obtaining the angle through which an auxiliary suspended magnet is deflected by the magnet used in the first part of the experiment.
Moreover, the imposing catalogue set on foot in 1865 at thirteen observatories by the German astronomical society has recently been completed; and adjuncts to it have, from time to time, been provided in the publications of the royal observatories at Greenwich and the Cape of Good Hope, and of national, imperial and private establishments in the United States and on the continent of Europe.