Political disturbances, always ruinous to the calm researches of the man of science, for many years prevented Humboldt carrying his wishes into effect; and it was not until 1828 that he was enabled to erect a small observatory at Berlin, whose more immediate object was to institute a series of simultaneous observations at concerted hours at Berlin, Paris, and Freiburg. In 1829 magnetic stations were established throughout Northern Asia, in connection with an expedition to that country which emanated from the Russian government; and in 1832 M. Gauss, the illustrious founder of a general theory of terrestrial magnetism, established a magnetic observatory at Göttingen, which was completed in 1834, and furnished with his ingenious instruments. In 1836 Baron Humboldt addressed a long and highly-interesting letter to the Duke of Sussex, then president of the Royal Society, urging the establishment of regular magnetical stations in the British possessions in North America, Australia, the Cape of Good Hope, and between the tropics, not only for the observation of the momentary perturbations of the needle, but also for that of its periodical and secular movements. This appeal was nobly responded to. The Royal Society, in conjunction with the British Association, called on government to advance the necessary funds to establish magnetical observatories at Greenwich, and in various parts of the British possessions; and in 1839-40 magnetical establishments were in activity at St. Helena, the Cape of Good Hope, Canada, and Van Diemen’s Land. The munificence of the directors of the East India Company founded and furnished, at the request of the Royal Society, magnetic observatories at Simla, Madras, Bombay, and Singapore, and the observations will be published in a similar form to those of the British observatories. We will now briefly describe the scheme of observations, and the manner of making them in the different observatories.