OF AGRICULTURE. 39 



duty to deliver. In fact, whilst I shall not neglect 

 important results and conclusions established by 

 others, the plan which I have in view will never- 

 theless involve much reliance on the data acquired 

 at Rothamsted. 



I may premise that since July 1855, when a new 

 laboratory, built by public subscription of agricul- 

 turists, was presented to Mr. Lawes, the old barn 

 laboratory has been abandoned. At the present 

 time, the Rothamsted staff consists of two, and some- 

 times three chemists; several general assistants in 

 different departments ; occasionally a botanical assist- 

 ant ; three, and sometimes four, computors and record 

 keepers; also a laboratory man, and several boys. 



The general scope and plan of the field-experiments 

 has been — to grow some of the most important crops 

 of rotation, each separately, year after year, for many 

 years in succession on the same land, without manure, 

 with farmyard manure, and with a great variety of 

 chemical manures ; the same description of manure 

 being, as a rule, applied year after year on the same 

 plot. Experiments, with different manures on the 

 mixed herbage of permanent grass-land, on the effects 

 of fallow, and on an actual course of rotation, without 

 manure, and with different manures, have likewise 

 been made. 



Field-experiments have thus been conducted for 

 the periods, and over the areas, indicated in the 

 table on the following page. 



Samples of all the experimental crops are brought 

 to the laboratory. Weighed portions of each are 

 partially dried and preserved for future reference, or 

 analysis. Duplicate weighed portions of each are 

 dried at ioo°C, the dry matter determined, and then 

 burnt to ash. The quantities of ash are determined 



