SKETCH OF ASAPH HALL. 837 



to observe a transit of Venus. He visited China and Japan on the 

 way. In 1878 he headed an expedition to Colorado to observe the 

 eclipse of the sun, and in 1882 he took a party to Texas to observe 

 another transit of Venus. 



Although on these expeditions he did valuable service, it has 

 been at Washington with the twenty-six-inch equatorial that he 

 has done his most important work. He has made studies of many 

 double stars, to determine their distances and motions. He has 

 also given a great deal of time to the study of the planet Saturn. 

 He made an especial investigation of the rings of this planet, and 

 also discovered the motion of the line of apsides of Hyperion, one 

 of Saturn's satellites. But by far the most important discovery 

 he has made, the one that will connect his name with astronomy 

 as long as the planets exist, was his discovery of the satellites of 

 Mars. It had been thought by some old astronomer that perhaps 

 Mars had satellites, but no one had been able to find them. In 

 the fall of 1877 Mars was in a very favorable position to observe, 

 and Prof. Hall turned his big telescope upon it. He searched 

 night after night without finding anything new. He began to 

 give up hope ; but on the night of August llth he discovered a 

 little speck that turned out to be the outer satellite. Six days 

 later he discovered the inner one. The discovery of these two 

 little bodies (the smaller one being not more than fifteen miles 

 in diameter) spread quickly among the observatories. The eager 

 astronomers immediately began to find enough extra moons to 

 supply another solar system. One observer insisted that there 

 was one more moon at least, and Prof. Hall was blamed as stupid 

 for not seeing it. But after a thorough investigation it was shown 

 that Prof. Hall had discovered the two and the only two satellites 

 of Mars. 



This important discovery brought his name at once before the 

 world at large, and was not slow in earning its reward. The Royal 

 Astronomical Society presented him with a gold medal, and he 

 was given the Lalande prize from Paris. Since that time his 

 work has been recognized as it should. He has become a member 

 of the most important scientific societies of this country, and an 

 honorary member of the royal scientific societies of England and 

 Russia and of the French Academy. The universities of the 

 country have recognized his work, Yale and Harvard each giving 

 him the degree of LL. D. The very last honor conferred upon 

 him is the Arago medal, just awarded to him by the French 

 Academy of Sciences. 



Personally, Prof. Hall is a fine-looking man. He is tall and 

 broad-shouldered. His forehead is high and deep. His eyes are 

 clear and bright, in spite of years spent in gazing at the stars. 

 He has always been strong and healthy. He is fond of the open 



