From the commencement of the work it was felt that the task was one which no man, though he were far better equipped and much more conveniently situated than the present writer, could satisfactorily accomplish from his own resources, and help was sought on special points wherever it seemed likely to be found.  In scarcely any quarter was the application made in vain.  Some who have aided most materially are indeed very old and valued friends; but to many others who have done the same the applicant was unknown; and some of these again, with whom the editor began correspondence on this subject as a stranger, he is happy to think that he may now call friends.

To none am I more indebted than to the Comm.  GUGLIELMO BERCHET, of Venice, for his ample, accurate, and generous assistance in furnishing me with Venetian documents, and in many other ways.  Especial thanks are also due to Dr. WILLIAM LOCKHART, who has supplied the materials for some of the most valuable illustrations; to Lieutenant FRANCIS GARNIER, of the French Navy. the gallant and accomplished leader (after the death of Captain Doudart de la Gree) of the memorable expedition up the Mekong to Yun-nan; to the Rev. Dr. CALDWELL, of the S.P.G.  Mission in Tinnevelly, for copious and valuable notes on Southern India; to my friends Colonel ROBERT MACLAGAN, R.E., Sir ARTHUR PHAYRE, and Colonel HENRY MAN, for very valuable notes and other aid; to Professor A. SCHIEFNER, of St. Petersburg, for his courteous communication of very interesting illustrations not otherwise accessible; to Major-General ALEXANDER CUNNINGHAM, of my own corps, for several valuable letters; to my friends Dr. THOMAS OLDHAM, Director of the Geological Survey of India, Mr. DANIEL HANBURY, F.R.S., Mr. EDWARD THOMAS, Mr. JAMES FERGUSSON, F.R.S., Sir BARTLE FRERE, and Dr. HUGH CLEGHORN, for constant interest in the work and readiness to assist its progress; to Mr. A. WYLIE, the learned Agent of the B. and F. Bible Society at Shang-hai, for valuable help; to the Hon. G. P. MARSH, U.S.  Minister at the Court of Italy, for untiring kindness in the communication of his ample stores of knowledge, and of books.  I have also to express my obligations to Comm.  NICOLO BAROZZI, Director of the City Museum at Venice, and to Professor A. S. MINOTTO, of the same city; to Professor ARMINIUS VAMBERY, the eminent traveller; to Professor FLUeCKIGER of Bern; to the Rev. H. A. JAESCHKE, of the Moravian Mission in British Tibet; to Colonel LEWIS PELLY, British Resident in the Persian Gulf; to Pandit MANPHUL, C.S.I. (for a most interesting communication on Badakhshan); to my brother officer, Major T. G. MONTGOMERIE, R.E., of the Indian Trigonometrical Survey; to Commendatore NEGRI the indefatigable President of the Italian Geographical Society; to Dr. ZOTENBERG, of the Great Paris Library, and to M. CH.  MAUNOIR, Secretary-General of the Societe de Geographie; to Professor HENRY GIGLIOI, at Florence; to my old friend Major-General ALBERT