22O SAMUEL PIERPONT LANGLEY. 



was shown when he secured a large portion of the money 

 required for the equipment of the observatory by " selling time" 

 to the railroads, a plan which resulted in great practical comfort 

 to travellers by establishing a uniform time system, and finally 

 by the standardization of time throughout the United States. 



Mr. Langley 's studies were largely directed to the sun, more 

 especially to that part of the sun's energy known as the infra- 

 red, for the investigation of which he invented a delicate instru- 

 ment, the bolometer, now universally employed by astronomers. 

 He aided and conducted numerous expeditions to observe the 

 eclipses of the sun, the study of the corona and other phenom- 

 ena, and in every case he secured successful results. Having 

 great charm as a popular lecturer and possessing a singularly 

 clear and beautiful literary style, he popularized the modern in- 

 vestigation of the sun and the science of astrophysics in his 

 work " The New Astronomy," probably the most distinguished 

 scientific memoir, from the literary point of view, ever produced 

 by an American. 



While still at Allegheny, Mr. Langley conducted a series of 

 experiments which led to his further work in Washington in 

 the solution of the problem of flying machines, or aerodromes, 

 as he called them. After numerous experiments he succeeded, 

 in 1896, in causing a steam driven machine, many times heavier 

 than the air, to make a free flight of over three-fourths of a 

 mile, and this was followed by another successful flight. These 

 performances were afterwards repeated many times with aero- 

 dromes propelled by both steam and gas driven engines, so that 

 to Mr. Langley will forever belong the credit of being the first 

 to successfully maintain in the air a mechanical device many 

 times heavier than the atmosphere, thus practically demonstrat- 

 ing the possibility of artificial flight. He later constructed a 

 large aerodrome, capable of carrying a man, actuated by a 52 

 horse-power gasoline engine, which unfortunately on two occa- 

 sions failed to be successfully launched. 



After serving for a short time as Assistant Secretary of the 

 Smithsonian Institution, in 1887 Mr. Langley succeeded Spencer 

 F. Baird in his office as Secretary. During his administration 

 the one large addition to the fund, since the foundation of the 



