A part, but only a part, of this great expedition has been described by him in various works. In the year 1840 appeared the first of the four volumes on Cashmere and the country of the Sikhs; in the years 1850–52 his treatise on the basin of the Cabul and the mountains between the Hindu-Kusch and the Sutlej was published in the Memoirs of the Imperial Academy of Sciences of Vienna. The latter is a work of geographical and historical importance. It is the first description, from the pen of a conscientious observer, of the formation and features, the fortunes and the circumstances, of this part of the south-western declivities of the mightiest elevation of Asia, and indeed of the world; a country which has played an important part in the history of the great military expeditions of all times.
Twenty years after 'Cashmere' was published, an account of an earlier part of his expedition appeared, under the title of "The Pacific Ocean and the Spanish Possessions in the East Indian Archipelago." This account, printed for private circulation, was dedicated to the Archduke Maximilian, who, himself a great traveller, had given proof of very brilliant gifts. The Preface, in which the author explains the cause of the late appearance of the book, shews his impartiality and his sense of justice. He says: "In face of the thoughtless charges of recent travellers, and of the malicious accusations of ancient rivals, I think it only right to raise a voice, however feeble, in favour of the colonial policy of Spain. My opinion is, at all events, the impartial opinion of an independent traveller. For years, and in all parts of the globe, the guest of Englishmen, of that mighty people whose grand views of life actuate each of its members, I feel myself deeply indebted to them for friendly reception and help, without which a part of my travels would have taken double the time, and a part would have
