To each writer, and especially to Dr. Alex. Bain, Mr. R. E. Francillon, Mark Twain, Mr. E. O'Donovan, Mr. J E. Boehm, Professor Dowden, the Rev. Dr. Martineau, Count Gubernatis, the Abbe Moigno, and Professor Magnus, who have shown hearty interest in the enquiry, I tender my best thanks for contributing to the solution of the important problem of the value of stimulants; also to Mr. W. E. A. Axon for suggestive and much appreciated help. I should, however, be glad of further testimonies for use in a second edition. _January_, 1883. CONTENTS. I. Introduction II. LETTERS FROM: Abbot, The Rev. Dr. Allibone, Mr. S. Astin Argyll, The Duke of, F. R. S. Arnold, Mr. Matthew Ayrton, Professor Bain, Dr. Alexander Ball, Professor Robert S., LL. D., F. R. S. Bancroft, Mr. Hubert Howe Baxendell, Mr. Joseph, F. R. A. S. Beard, Dr. G. M. Bert, Professor Paul Blackie, Professor John Stuart Blanc, M. Louis Boehm, Mr. J. E., R. A. Bredencamp, Dr. Brown, Mr. Ford Madox, R. A. Buchanan, Mr. Robert Buddenseig, Dr. Burnaby, Captain Fred Butler, Lieut. Col. W. F. Burnton, Dr. Lauder, F. R. S. Camp, Madame du Carpenter, Dr. W. B., C. B., LL. D., F. R. S. Chambers, Mr. William, LL. D Childs, Mr. George W. Claretie, M. Jules Clarke, Mr. Hyde, F. S. S. Collins, Mr. Wilkie Conway, Mr. Moncure D., M. A. Dallenger, Rev. W. H., F. R. S Darwin, Professor Dawkins, W. Boyd, M. A., F. R. S., F. G. S. D'Orsey, The Rev. Alex. J. D., B. D. O'Donovon, Mr. Edmund Dowden, Professor, LL. D. Edison, Professor Ellis, Mr. Alex. J., F. R. S., F. S. A. Everett, Professor Fairbairn, Professor R. M. Francillon, Mr. R. E. Freeman, Mr. Edward A., D. C. L., LL. D. Furnivall, Mr. F. J., M. A. Gardiner, Mr. Samuel R., Hon. LL. D. Gladstone, Rt. Hon. W. E., M. P. Greville, Mdlle. II Gubernatis, Count Guenin, M. L. P. Guy, Dr. William Haeckel, Professor Ernst Hamerton, Mr. Philip Gilbert Hardy, Mr. Thomas Harrison, Mr. Frederic Henty, Mr. G. A. Holmes, Mr. Oliver Wendell Holyoake, Mr. George Jacob Hooker, Sir J. D., F. R. S. Howells, Mr. W. D. Joule, Dr. J. P. Lansdell, The Rev. Henry Leathes, Rev. Stanley, D. D. Lecky, W. E. H. Lees, Dr. F. R. Levi, Mr. Leone, F. S. A. Lubbock, Sir John, Bart. M. P. Magnus, Professor Maitland, Mr. Edward, B. A. Martin, Sir Theodore, K. C. B. Martineau, The Rev. James, D. D. Maudsley, Dr. Henry May, Sir Thomas Erskine, K. C. B., D. C. L. Mayor, Rev. John E. B., M. A. Moigno, The Abbe Morrison, Rev. J., D. D. Mongredien, Mr. Augustus Murray, Dr. J. A. H. Murray, Mr. D. Christie. Newman, Professor Pattison, The Rev. Mark, B. D. Payn, Mr. James Pitman, Mr. Eizak Plaute, M. Gaston Plummer, The Rev. A. Pocknell, Mr. Edward Rawlinson, Professor George Reade, Mr. Charles Reed, Mr. Thomas Allen Rodenberg, Dr. Julius Russell, Dr. W. H. Ruskin, Mr. John Sen, Keshub Chunder Simon, M. Jules Skeat, Professor St. Hilaire, M. Barthelemy Spottiswoode, Mr. W., D. C. L., LL. D.