836 THE POPULAR SCIENCE MONTHLY. 



and meanness were rife in the departments of the Government. 

 But he kept out of all disputes and settled down quietly to his 

 work. 



On January 2, 1863, he was appointed a Professor of Mathe- 

 matics in the United States Navy. After that his career was as- 

 sured, for his position was for life. Starting as a farmer boy, then 

 turning carpenter, pursuing mathematics with the idea of be- 

 coming an architect, finally he had found the best field for his 

 labor in astronomy. Up to this time his struggle was a hard one. 

 He had never known what it was to have a moment of relaxation. 

 It was toil from morning till night, and all that he did was for 

 the personal benefit of others. After his appointment at Wash- 

 ington he was able to do work that counted for himself. So his 

 public scientific career really began in 1862. 



From 1862 to 1866 he worked on the nine-and-a-half -inch equa- 

 torial at the Naval Observatory under Mr. James Ferguson, mak- 

 ing observations and reducing his work. One night, while he was 

 working alone in the dome, the trap-door by which it was entered 

 from below opened, and a tall, thin figure, crowned by a stovepipe 

 hat, arose in the darkness. It turned out to be President Lincoln. 

 He had come up from the White House with Secretary Stanton. 

 He wanted to take a look at the heavens through the telescope. 

 Prof. Hall showed him the various objects of interest, and finally 

 turned the telescope on the half-full moon. The President looked 

 at it a little while and went away. A few nights later the trap- 

 door opened again, and the same figure appeared. He told Prof. 

 Hall that after leaving the observatory he had looked at the 

 moon, and it was wrong side up as he had seen it through the 

 telescope. He was puzzled, and wanted to know the cause, so he 

 had walked up from the White House alone. Prof. Hall explained 

 to him how the lens of a telescope gives an inverted image, and 

 President Lincoln went away satisfied. 



After 1866 Prof. Hall worked as assistant on the prime vertical 

 transit and the meridian circle. In 1867 he was put in charge of 

 the meridian circle. From 1868 to 1875 he was in charge of the 

 nine-and-a-half -inch equatorial, and from 1875 until his retirement 

 on October 15, 1891, he was in charge of the twenty-six-inch equa- 

 torial. It can thus be seen that his practical experience as an 

 observing astronomer has been long and varied. 



During his stay at the observatory he was sent on several ex- 

 peditions for the Government. In 1869 he was sent to Bering 

 Strait on the ship Mohican to observe an eclipse of the sun. In 

 those days one had to go to San Francisco by way of the Isthmus 

 of Panama; all the instruments had to be sent the same way so 

 it was a big undertaking. In 1870-'71 he was sent to Sicily to ob- 

 serve another eclipse. In 1874 he went to Vladivostock, in Siberia, 



