124 A CENTURY'S PROGRESS IN ASTRONOMY. 



addition to considerable mathematical powers, 

 was an enthusiastic lover of astronomy. At 

 the age of thirteen young Olbers became deeply 

 interested in that science. While taking an 

 evening walk in the month of August, he 

 observed the Pleiades, and determined to find 

 out to which constellation they belonged. He 

 therefore bought some books on astronomy, 

 along with a few charts of the sky, and he 

 began to study the science with much en- 

 thusiasm. He read every book he could lay 

 his hands on, and a few months sufficed to 

 make him acquainted with all the constellations. 

 In 1777, when in his nineteenth year, 

 Olbers entered the University of Gottingen 

 to study medicine, and at the same time 

 he learned much regarding mathematics and 

 astronomy from the mathematician Kaestner. 

 When twenty - one years of age he observed 

 the stars at Gottingen, and devised a method 

 of calculating the orbits of comets, the idea 

 coming to him while he was attending at the 

 bedside of a fellow -student who had taken ill. 

 "Although not made public until 1797," writes 

 Miss Clerke, "' Olbers' method' was then uni- 

 versally adopted, and is still regarded as the 

 most expeditious and convenient in cases where 

 absolute rigour is not required. By its intro- 



