CHAPTER IV. 



YEARS OF BLINDNESS (Continued}', THE CLASS-BOOK OF 

 CHEMISTRY. 



1845-1851. Age, 24-30. 



IN the summer of 1846 Mr. Youmans had a long 

 period of total blindness, and two members of the 

 Ketcham household, who rendered him much service 

 in reading and in leading him through the streets, 

 were obliged in the autumn to leave New York. He 

 now wrote to his sister, asking her if she could come 

 to New York to set free his friends from their care of 

 him, and to aid him in some projected literary work. 

 She went to him at once, and was pleased to find, not- 

 withstanding the despondent tone of his letters, that 

 his personal charm had drawn about him so many 

 helpful friends. 



He had several literary projects to lay before his 

 sister, the chief of which was a history of progress in 

 discovery and invention, and upon this book work 

 was forthwith begun. Despite all obstacles, he had 

 year by year contrived to pick up a good deal of in- 

 formation regarding scientific progress all along the 

 line ; and the themes which he now discussed with 

 most animation were those suggested by modern 

 geology and the nebular theory. Are Nature's laws 

 uniform ? Is the universe vastly older than has been 

 supposed? These were grave questions to a man 



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