Unlike some other reproductions of classic texts (1) We have not used OCR(Optical Character Recognition), as this leads to bad quality books with introduced typos. (2) In books where there are images such as portraits, maps, sketches etc We have endeavoured to keep the quality of these images, so they represent accurately the original artefact. Although occasionally there may be certain imperfections with these old texts, we feel they deserve to be made available for future generations to enjoy.

As early as the seventeenth century, scientists realised that a pendulum swings more slowly at the equator than it would at the North Pole. Newton predicted that gravity increased with latitude, and that the Earth could not be perfectly spherical. Although various experiments were undertaken to determine the exact degree of this ellipticity, none proved successful until physicist Edward Sabine (1788-1883) embarked on a series of expeditions across the world. Based on pendulum measurements from a wide range of latitudes, from Jamaica to Spitsbergen, his results were very different to mathematical predictions, and far more accurate; Charles Babbage would even complain that they were too good to be true. In this account, which first appeared in 1825, Sabine explains his methodology and presents his findings. His book opens a fascinating window into nineteenth-century geodesy for students in the history of science.

The explorer, soldier and geophysicist Sir Edward Sabine (1788 1883) served as astronomer on John Ross's 1818 expedition in search of the North-West Passage. His return to the Arctic, under William Parry in 1819 20, compounded a keen interest in geomagnetism and his publications earned him the Copley Medal of the Royal Society (whose presidency he would later hold). His experience and expertise made him a natural editor, therefore, of this Arctic narrative, translated into English from German by his wife, Elizabeth Juliana Leeves (1807 79), and published in 1840. It is the account by Ferdinand von Wrangell (1797 1870), a Russian explorer of Baltic German ancestry, regarding his expedition to survey Siberia's north-eastern coastline. Compiled from the notes of the scientists on board, this work offers a valuable and wide-ranging insight into an inaccessible and little-known portion of the globe.

Alone, months of sailing separating them from home, in the polar winter where the sun never rises, the two ships of Captain William Parry's expedition lay encased in ice from November 1819 to March 1820. In order to fully chart the North-West Passage between the Atlantic and the Pacific, it was necessary to overwinter in the Arctic, something that no other British expedition had done before. To boost morale in these uncomfortable circumstances, Captain Edward Sabine (1788-1883), a senior scientist carrying out measurements of natural phenomena, founded and edited a weekly magazine, which ran for twenty-one issues and was made available to the wider world in 1821. Offering jokes, poems, stories and thinly disguised gossip, the members of the expedition contributed to the magazine with enthusiasm (after having first thawed their ink). This little book offers unique insight into what polar exploration in the nineteenth century was actually like.

Polymath Alexander von Humboldt (1769 1859), a self-described 'scientific traveller', was one of the most respected scientists of his time. Humboldt's wanderlust led him across Europe and to South America, Mexico, the U.S., and Russia, and his voyages and observations resulted in the discovery of many species previously unknown to Europeans. Originating as lectures delivered in Berlin and Paris (1827 1828), his multi-volume Cosmos: Sketch of a Physical Description of the Universe (1845 1860) represented the culmination of his lifelong interest in understanding the physical world. As Humboldt writes, 'I ever desired to discern physical phenomena in their widest mutual connection, and to comprehend Nature as a whole, animated and moved by inward forces.' Volume 1 (1846) investigates celestial and terrestrial phenomena, from nebulae to the temperature of the earth, as well as 'organic life'. Throughout, he stresses the method of, and limits to, describing the universe's physical nature.

Polymath Alexander von Humboldt (1769 1859), a self-described 'scientific traveller', was one of the most respected scientists of his time. Humboldt's wanderlust led him across Europe and to South America, Mexico, the U.S. and Russia, and his voyages and observations resulted in the discovery of many species previously unknown to Europeans. Originating as lectures delivered in Berlin and Paris (1827 1828), his two-volume Cosmos: Sketch of a Physical Description of the Universe (1845 1860) represented the culmination of his lifelong interest in understanding the physical world. As Humboldt writes, 'I ever desired to discern physical phenomena in their widest mutual connection, and to comprehend Nature as a whole, animated and moved by inward forces'. Volume 2 (1848) reviews poetic descriptions of nature as well as landscape painting from antiquity through to modernity, before using the same time-span to examine a 'History of the Physical Contemplation of the Universe'.