Only recorded copy of the 1848 edition (preceded only by one recorded copy of 1846 edition) of Malby's 18 inch (45.5 cm) terrestrial globe, the largest he engraved and much rarer than his 12 inch globe. It shows small pieces of the Antarctic coast, noting sightings and explorations from 1831 to 1841. In Africa it shows Lake "Nyassi" (Nyasa or Malawi), discovered by Candido José da Costa Cardoso in 1846, but most of equatorial Africa and the Congo remain uncharted territory, with Burton and Speke's most important discoveries still a decade in the future and Stanley's even further. "Oregon", officially made a United States territory in 1848, shows the boundary with "British America" agreed at the 1846 Oregon treaty. Alaska is still "Russian America", not to be purchased by the United States until "Seward's folly" in 1867. Texas is part of the United States, reflecting the demise of the "Lone Star" Texas Republic in 1845/46, as are California and most of Arizona, which Mexico ceded in the Treaty of Guadalupe Hidalgo on 2 February 1848. The Revolution of 1848 has not yet affected the boundaries of the Austrian Empire. "Debai" (Dubai) is shown on the Gulf coast, only 15 years after the al-Maktoum dynasty took charge of it in 1833. The globe seems to be intended especially for navigational use, with not only a grid of parallels and meridians (with the prime meridian through Greenwich), but also the irregular curved lines indicating the variation of magnetic from geographic north ("isogones"), at 5 degree intervals. From these one can clearly see where the magnetic poles were. Edmund Halley produced the first world map with isogones in 1702, but the Pacific had to wait until Nicolaas van Ewyk's 1752 map of the northern and southern hemispheres. Malby cites Peter Barlow in the 1833 Transactions of the Royal Society for his data. Where these lines run at least partly north-south, mariner's could use them to help determine longitude. The discovery that they were nearly horizontal in many parts of the East Indies and Pacific, and that they could also change over time, lead to their declining use after John Harris's chronometer came into use beginning around 1772. Malby seems to be the first and almost the only globe maker to show them. The engraver signed the present globe "Chas. Malby" and signed the 12 inch globe of 1845 described by Dekker "C. I. Malby". He must therefore have been Charles Isaac Malby (1816-post 1868), born in London, the son of Thomas and Elizabeth Malby. Thomas Malby, Charles's brother, born in London in 1808, first set up as a globe publisher around 1839 and was trading as Malby & Co by 1841. Charles may have engraved nearly all of his globes. In 1848/49 Thomas took his son Thomas Henry (born 1828) into partnership as Thomas Malby & Son and the firm traded as Malby & Son, to about 1880. They issued a 36 inch (92 cm) globe in 1849, but did not engrave it themselves, having acquired the plates of John Addison's ca. 1825 globe for that size. The earliest Malby globe known to survive is dated 1842, but his earliest recorded 18 inch globes are a pair at the Mariners' Museum in Virginia: the celestial globe dated 1843 and the terrestrial globe dated 1846. The Austrian National Library has an 18 inch Malby terrestrial globe dated 1850, but we find no further example until 1872. The present 1848 example appears to be unique. The Willis Museum in Basingstoke, England, and Dartmouth College in New Hampshire have examples of Malby's 18 inch celestial globe dated 1848, but neither is accompanied by a terrestrial globe. The horizon ring has an owner's stamp on the printed surface, nearly due east, apparently a coat of arms in a wreath, but difficult to make out. The horizon ring and globe have a dozen small cracks repaired and a few small gaps in the surface image, some repaired, but are otherwise in good condition. Extremely rare and lovely large globe, with the fascinating and unusual graphic presentation of geomagnetism.
¶ Cf. British Library on-line cat. BLL01013005847 (12 inch, 1869 & 18 inch, 1872); Dekker, GLB0081 (12 inch, 1845); Dunn & Wallis, British globes up to 1850 (1999) 209 (18 inch, 1846, 1 example) & 443 (18 inch celestial globe, 1848, 2 copies); KVK & WorldCat (18 inch, 1850 & 1872, 1 example of each); World in your hands (Rudolph Schmidt coll.) 7.12 & 7.13 (12 inch, 1843 & 1860); (18 inch celestial globe, 1853); Yonge, Early globes (1968), p. 46 (18 inch, 1846, same example as Dunn & Wallis).