xxxiv Annual Report of the Council. 



many thousands of years, no indication was found of any such 

 origin. Whilst Newcomb could not be said to have settled the 

 matter one way or the other by the investigation, he clearly 

 showed in it that grasp of the general principles of celestial 

 mechanics which was the keynote of his life's work. 



Whilst engaged in the Observatory at Washington he appears 

 to have formed two plans for his future work, one being the 

 preparation of constants of astronomy, and the other the theory 

 of the moon's motion. In connection with the first he took up 

 the question of the sun's distance, which fiom observations of 

 Mars in 1862 he made out to give a parallax of 8""848. This, 

 however, he abandoned later for the value 8"79o, which is very 

 close to the latest determination by Hinks. His. paper on the 

 Asteroids was followed by " An Investigation of the Orbit of 

 Neptune" in 1867 and "An Investigation of the Orbit of 

 Uranus " in 1874. 



In 1870 he took up the important subject of the Moon's 

 motion, and his results were published eight years later, some of 

 them being used in our own Nautical Almanac. In this year 

 he first visited Europe and was introduced to many eminent 

 Astronomers both in this country and on the Continent. The 

 Franco-German war was proceeding, but facilities were afforded 

 him for inspecting the Paris Observatory records of the moon's 

 motion, and much of this investigation was made within hearing 

 and sight of the guns around Paris. 



In the period between 1861 and 1877 short notes from him 

 appeared on a variety of subjects — optics, finance, taxation, 

 social science, the labour question, copyright, political economy, 

 non-Euclidean geometry, besides numerous reviews and popular 

 articles. 



Whilst at the Naval Observatory he played a very important 

 part in connection with the 26 inch telescope, the then largest 

 instrument in the world, having to select and test the glasses. 

 Later he was also consulted by the Russian and Japanese 

 governments in a similar connection. In 1878 he published 

 his "Popular Astronomy," and in 1884 his "Measure of the 



