6 9 + THE POPULAR SCIENCE MONTHLY. 



lagers went back to their homes, and Joseph and his sisters re- 

 mained some time in the little village of Ohain. 



As soon as his health was restored he returned to his art 

 studies. Here he made such excellent progress that one evening 

 Prince Frederick, the son of the king, who was visiting the estab- 

 lishment, was attracted by the boy's work. When he found that 

 Joseph was an orphan, he said, " Well, from this moment I take 

 you under my protection." Later, when M. Thirion wished to 

 remind the prince of his promise, he was deterred by the boy's 

 unwillingness to make any claim upon him. 



Painting occupied Joseph by day, but in the evening and in 

 his leisure moments his beloved physics employed all his time. 

 With the aid of some young friends he organized soirees, the en- 

 tertainment being experiments of his own devising, made with 

 apparatus constructed by himself. 



At sixteen years of age he entered the Athenaeum at Brussels. 

 He omitted certain studies, but in all that he undertook he dis- 

 tinguished himself by his enthusiastic progress. His masters 

 became at once interested in their brilliant pupil. The friendship 

 of Quetelet, which became stronger as time went on, proved of 

 the greatest benefit to him in later life. 



His school-life over, the subject of a profession presented itself 

 for reconsideration. His uncle pressed upon the boy the study of 

 law, as the noblest of all professions, and Joseph consented. In 

 choosing art there had been no great sacrifice ; he had been too 

 young at that time to know his own mind ; but he felt a strong 

 antipathy to the law. 



This dislike did not prevent honest and conscientious work in 

 the pursuit of his legal studies ; but the physical sciences held for 

 him their old fascination, and he made the rather singular com- 

 promise of studying both law and physics, and doing himself 

 credit in both alike. His faithful work had its reward at last : 

 his uncle, seeing his determination, and at the same time his will- 

 ingness to be guided, withdrew his opposition, and the young stu- 

 dent gave himself up wholly to scientific pursuits. 



The care of his younger sister now fell upon Plateau, and, 

 pressed by the necessity to provide for them both, he accepted the 

 professorship of elementary mathematics in the Athenaeum at 

 Liege. This was in 1827. In 1829 he received the degree of 

 Doctor in Physical Sciences and Mathematics, and from that time 

 he gave himself to original research. 



During this year he devoted much time to experimenting upon 

 various points in regard to vision, to the persistence of impres- 

 sions upon the retina, subjective color, etc. On one occasion, to 

 determine some point, he looked at the sun for twenty-five sec- 

 onds with the naked eye. For many days after this hazardous 



