Page:Popular Science Monthly Volume 45.djvu/858

836 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 Mathematics in the United States Navy. After that his career was assured, for his position was for life. Starting as a farmer boy, then turning carpenter, pursuing mathematics with the idea of becoming 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 Washington 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 equatorial at the Naval Observatory under Mr. James Ferguson, making 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 trapdoor 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 equatorial. 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 expeditions 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 observe another eclipse. In 1874 he went to Vladivostock, in Siberia,