164 LETTER-FILES OF S. W. JOHNSON 



Professor George H. Cook of Rutgers College wrote 

 from the office of the State Geological Survey, on Sep- 

 tember 18, 1869, commenting with approval on the 

 report, and saying: 



Your straightforward estimate of the value of different fer- 

 tilizers is producing a sensation among both manufacturers 

 and consumers, and will be of great service to Agriculture. 



He closed his letter with this sentence: 



The circulation of such reports as that of yours on fertilizers 

 will be of great use, and I hope you will be allowed to con- 

 tinue making full and fearless reports on the worthless 

 manures which are so common in market. 



Professor Johnson had altered and improved the 

 text of "How Crops Feed" almost up to the moment 

 of stereotyping the pages; when its publication 

 relieved this strain, he found that nerve exhaustion 

 complicated the malaria with which he had suffered 

 for several years. A camping trip in the Adirondacks 

 improved his apparent condition, and he returned in 

 the fall of 1870 to his college duties, lightened to some 

 extent, as he was now relieved from daily superin- 

 tendence of the analytical laboratory. He wrote on 

 September 20: 



The Laboratory is getting on nicely with Allen at the head. 

 I have five exercises weekly (2 ag. chem. and 2 analyt. chem.) 

 coming at 10 o'clock each weekday except Friday. I am now 

 ready, all except health, to renew the text-book work. ! I 

 would that it were off my hands ! 



During the winter he refrained from all save class- 

 room work, but notwithstanding careful living and the 



