n8 THE POPULAR SCIENCE MONTHLY. 



1877, and, on its going into effect, Prof. Johnson was appointed 

 director. " For many years," says the Rural New-Yorker, " the 

 station was confined to two small rooms, and the appliances and 

 works of reference were for the most part loaned from Yale 

 College or borrowed from the professor's private laboratory and 

 library." 



Mr. Johnson began his literary work while still a student, 

 writing for the agricultural papers. Among the earliest of his 

 publications of general interest was an address before the State 

 Agricultural Society of Connecticut, in 1866, on Fraud in Chem- 

 ical Fertilizers. This was followed by the adoption of measures 

 intended to protect buyers of fertilizers against imposition through 

 adulterations. As chemist to the State Agricultural Society he 

 made a series of reports on fertilizers in 1857, 1858, and 1859, by 

 means of which knowledge on the subject was extended, and 

 frauds received a further check. Besides his official reports, 

 " which have been models for works of their kind," Prof. John- 

 son's writings include many contributions to the agricultural 

 press, which have been highly appreciated, and several books on 

 the special subjects of his studies. The best known of these are 

 How Crops Grow ; How Crops Feed ; Peat and its Uses as Fer- 

 tilizer and Fuel. The earliest and best known of these books — 

 How Crops Grow, published in 1868 — embodied the results of 

 stvdies undertaken by the author in preparing instruction in 

 agricultural science. Together with its companion volume — How 

 Crops Feed — it was intended to present concisely but fully the 

 state of the science at the time regarding the nutrition of the 

 higher plants, and the relations of the atmosphere, water, and soil 

 to agricultural vegetation. In it the chemical composition of 

 agricultural plants was described in detail, the substances indis- 

 pensable to their growth were indicated, and an account was 

 given of the apparatus and processes by which the plant takes up 

 its food. The book was received with great favor in America and 

 in Europe. It was republished in England under the joint editor- 

 ship of Profs. Church and Dyer, of the Royal Agricultural Col- 

 lege at Cirencester ; a translation of it was published in Germany 

 under the instigation of Prof. Liebig ; and other versions of it 

 have been made in Swedish, Italian, and Japanese, and twice in 

 Russian. 



In view of the great advance that had been made in all branches 

 of science, a new edition of How Crops Grow was issued in 1890, 

 in which the purpose was guarded of bringing the treatise up to 

 date as fully as possible without greatly enlarging its bulk or 

 changing its essential character. 



The account of the sources of the food of plants, which were 

 noticed in this volume in only the briefest manner, was reserved 



