of that great soul, is a fit object for a nation’s care, as the achievements of the man are, or will one day be, the object of a nation’s pride and gratitude. THE CHINESE AND THE MAGNETIC NEEDLE. More than a thousand years before our era, a people living in the extremest eastern portions of Asia had magnetic carriages, on which the movable arm of the figure of a man continually pointed to the south, as a guide by which to find the way across the boundless grass-plains of Tartary; nay, even in the third century of our era, therefore at least 700 years before the use of the mariner’s compass in European seas, Chinese vessels navigated the Indian Ocean under the direction of Magnetic Needles pointing to the south. Now the Western nations, the Greeks and the Romans, knew that magnetism could be communicated to iron, and _that that metal_ would retain it for a length of time. The great discovery of the terrestrial directive force depended, therefore, alone on this--that no one in the West had happened to observe an elongated fragment of magnetic iron-stone, or a magnetic iron rod, floating by the aid of a piece of wood in water, or suspended in the air by a thread, in such a position as to admit of free motion.--_Humboldt’s Cosmos_, vol. i. KIRCHER’S “MAGNETISM.” More than two centuries since, Athanasius Kircher published his strange book on Magnetism, in which he anticipated the supposed virtue of magnetic traction in the curative art, and advocated the magnetism of the sun and moon, of the divining-rod, and showed his firm belief in animal magnetism. “In speaking of the vegetable world,” says Mr. Hunt, “and the remarkable processes by which the leaf, the flower, and the fruit are produced, this sage brings forward the fact of the diamagnetic (repelled by the magnet) character of the plant which was in 1852 rediscovered; and he refers the motions of the sunflower, the closing of the convolvulus, and the directions of the spiral formed by the twining plants, to this particular influence.”[45] Nor were Kircher’s anticipations random guesses, but the result of deductions from experiment and observation; and the universality of magnetism is now almost recognised by philosophers. MINUTE MEASUREMENT OF TIME. By observing the magnet in the highly-convenient and delicate manner introduced by Gauss and Weber, which consists in attaching a mirror to the magnet and determining the constant factor necessary to convert the differences of oscillation into differences of time, Professor Helmholtz has been able, with comparatively simple apparatus, to make accurate determinations up to the 1/10000th part of a second. POWER OF A MAGNET.