LETTER OF TRANSMITTAL. 
U. S. Department of Agriculture, 
Office of Experiment Stations, 
Washington, I). C, January 8, 1902. 
SlB: I have the honor to transmit herewith for publication as Bul- 
let in No. lot; of i his ( Hlice a scries of led ures on soil invest igat ions at 
Rothamsted, England, delivered ander the provisions of the Lawes 
Agricultural Trust, by Bernard Dyer, D. Sc., before the convention 
of the Association of American Agricultural Colleges and Experiment 
Stations at New Haven ami Middletown, Conn., November, 1901. 
These le<-i ures are recommended For publication in full, not only on 
account of their intrinsic value, but in conformity with the wish of the 
late Sir John I. awes, frequent 1 y expressed during the later years of 
his life, u i hat all siat ist ical matter reiai ing t<> observat ions ami exper- 
iments on the Rothamsted soils should be brought together (as he 
expressed it ) * bei ween one pair of covers.' " Tliese observal ions and 
experiments have extended over a number of years and have been 
partly published elsewhere, but by far the greater portion of the mat- 
ter contained in these lectures, including the results of the author's 
recent exhaust ive st udies on t he phosphoric acid and potash contents 
of Rothamsted soils, is new. It is fitting that ackowledgment should 
here be made of the munificence and splendid devotion to agricultural 
science which prompted Sir John Lawes not only to found and main- 
tain for many years, but to endow in perpetuity, the great experiment 
slat ion at Rot hamsted, and of t he kindly interest in American agricul- 
ture which led him at the same time to provide for a series of biennial 
lectures in the United Stales on the work of that station, in order, as 
he stated, that Americans might feel that they had a share in any of 
the benefits which might arise from the Rothamsted endowment. 
Since these lectures wnv prepared for publication, Sir J. Henry 
Gilbert, who for over fifty-five years was the associate of Sir* John 
Lawes at Rothamsted, has also passed away from the scene of his 
lifelong labors. He died on December 23, 1901, at the age of nearly 85 
years. 
The lectures transmitted herewith are the fourth of the courses so 
provided for and the third to be published as bulletins of this Depart- 
ment. The first course, delivered at Washington, D. C, August, 
1891, by Robert Warington, F. R. S., gave a brief account of the 
Rothamsted Experiment Station, but dealt mainly with the work of 
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