EEPORT OF THE SECRETAEY. 15 



Langley's " Experiments in Aerodynamics," and " The Internal 

 Work of the Wind," published in 1891 and 1893, respectively. The 

 present memoir was in preparation at the time of Mr. Langley's 

 death in 190G, and the part recording experiments from 1887 to 1896 

 was written by him. The chapters discussing experiments from 1897 

 to 1903 were written by Mr. Charles M. Manly^ who became chief 

 assistant to Mr. Langley in 1898. 



In the preface to the Memoir, Mr. Manly says: 



The present volume on IMecbanical Flight consists, as the title-page indicates, 

 of two parts. The first, dealing with the long and notable series of early ex- 

 periments with small models, was written almost entirely by Secretary Langley, 

 with the assistance of Mr. E. C. Huffaker and Mr. G. L. Fowler, in 1897. Such 

 chapters as were not complete have been finished by the writer and are easily 

 noted, as they are written in the third person. It has been subjected only to 

 such revision as it would have received had Mr. Langley lived to supervise this 

 publication, and has therefore the highest value as an historical record. The 

 composition of the second part, dealing with the later experiments with the 

 original aiid also new models and the construction of the larger aerodrome, has 

 necessarily devolved upon me. This is in entire accordance with the plan 

 formed by Mr. Langley when I began to work with him in ISOS, but it is to 

 me a matter of sincere regret that the manuscript in its final form has not had 

 the advantage of his criticism and suggestions. If the reader should feel that 

 any of the descriptions or statements in this part of the volume leave something 

 to be desired in fullness of detail, it is hoped that some allowance may be made 

 for the fact that it has been written in the scanty and scattered moments that 

 could be snatched from work in other lines which made heavy demands upon 

 the writer's time and strength. It is believed, however, that sufficient data 

 are given to enable any competent engineer to understand thoroughly even the 

 most complicated phases of the work. 



Persons who care only for the accomplished fact may be inclined to underrate 

 the interest and value of this record. But even they may be reminded that but 

 for such patient and unremitting devotion as is here enregistered the now 

 accomplishetl fact of mechanical flight would still remain the wild unrealized 

 dream which it was for so many centuries. 



To such men as Mr. Langley an unsuccessful experiment is not a failure, but 

 a means of instruction, a necessary and often an invaluable stepping stone to 

 the desired end. The trials of the large aerodrome in the autumn of 1903, to 

 which the curiosity of the public and the sensationalism of the new^spapers gave 

 a character of finality never desired by Mr. Langley, were to him merely mem- 

 bers of a long series of experiments, as much so as any trial of one of the small 

 aerodromes or even of one of the earliest rubber-driven models. Had his 

 health and strength been spared, he would have gone on with his experiments 

 undiscouraged by these accidents in launching and undeterred by criticism and 

 misunderstanding. 



Moreover, it is to be borne in mind that Mr. Langley's contribution to the 

 solution of the problem is not to be measured solely by what he himself accom- 

 plished, important as that is. He began his investigations at a time when not 

 only the general public but even the most progressive men of science thought of 

 mechanical flight only as a subject for ridicule, and both by his epoch-making 

 investigations in aerodynamics and by his devotion to the subject of flight 

 itself he helped to transform into a field of scientific inquiry what had before 

 been almost entirely in the possession of visionaries. 



