SAMUEL PIERPONT I.ANGLEY. 35 



His lack of success was probably due to the fact that, Hke Maxim, 

 Ader, Kress, and many others, he undertook too much at once by 

 endeavoring to produce a full-fledged dynamic flying-machine ab 

 initio, before making sure of the control, the stability, and the possi- 

 bility of alighting safely ; but he rescued the problem from contempt, 

 he laid the lines which must be followed, and, having published the 

 results of his experiments and given other men data upon which to 

 conquer the air, he will ever be remembered as the precursor and the 

 pathfinder of successful flying-machines. 



BIBLIOGRAPHY OF PUBLISHED WORKS OF S. P. 

 LANGLEY.i 



1869. Report by Professor S. P. Langley of Observations at Oakland, Ken- 

 tucky (eclipse of 1869). United States Coast Survey Observations 

 of Total Eclipse of August 7, 1869, pp. 21-22. 



1869. Allegheny Observatory. Proposal for regulating of clocks of railroads. 



Pamphlet, dated December i, 1869, pp. 1-8, pi. i. 



1870. Recent Discoveries in Astronomy. Report of the Teachers' Institute 



of Allegheny County. Tenth annual session, April 4-8, Pittsburgh, 

 1870, No. I, pp. 21-26. 



1870. Eclipse of 1870. Letter concerning eclipse at the Jerez de la Frontera, 



December 23, 1870. Journal of the Franklin Institute, Philadelphia. 



1871. The American Eclipse Expedition. Nature, London, January 19, 1871, 



vol. Ill, pp. 228-229. 

 1871. A New Form of Solar Eye-piece. Journal of the Franklin Institute, 



Philadelphia, 1871. vol. 51, pp. 115-117. 

 1871. Reports of Observations upon the Total Solar Eclipse of December 22, 



1870. Report of the United States Coast Survey, 1870, Appendix No. 



16, Washington, 1871, pp. 44-51, pi. i. 



1871. Reports of Observations upon the Total Solar Eclipse of December 22, 



1870. From the United States Coast Survey Report for 1870, Appen- 

 dix No. 16, pp. 44-51, pi. I. 



1872. Pittsburgh and the Longitude. Pittsburgh Gazette, April 27, 1872. 

 1872. On the Allegheny System of Electric Time Signals. American Journal 



of Science, New Haven, November, 1872, 3rd series, vol. iv. No. 23, 

 pp. 377-386. 



1872. On the Allegheny System of Electric Time Signals. Telegraph Engi- 



neers' Journal, 1872-73, vol. i, pp. 433-441. 



1873. The Planetary World. "Planetary Evolution" given in the Y. M. C. A. 



Free Course, April 15, 1873. Pittsburgh Gazette, April 16, 1873. 



'Prepared from Mr. Langley's personal set of his writings and other 

 sources, under the supervision of Mr. Paul Brockett, Assistant Librarian of 

 the Smithsonian Institution. Acknowledgment is made to Dr. John A. 

 Brashear, of Pittsburgh; Mr. Edward E. Eggers, of the Carnegie Free Li- 

 brary, Allegheny, Pa., and Mr. Anderson H. Hopkins, Librarian of the Car- 

 negie Library, Pittsburgh, Pa., for their assistance in securing citations from 

 publications issued in Pittsburgh not available at the Smithsonian Institution. 

 3 



