PREE ACE. 
Several experts in agricultural science having stated to me their 
need of a systematic summary of the present state of our knowledge 
with regard to the specific influence of climate in agriculture and its 
relation to or absolute effect on the percentages of the resulting har- 
vest, and the subject being one in which I had long been interested, 
I therefore presented the matter to the Chief Signal Officer, who 
thereupon issued an instruction, dated February 25, 1891, authorizing 
me to prepare this work, completing it before June 30 of that year. 
The present report is a rapid compilation from a wide range of 
sources, and presents a preliminary view of the condition of our 
knowledge at that time as to the effect of climate upon the growth 
and distribution of our staple crops. As far as practicable I have 
presented, in the words of the respective authors, the results of their 
own investigations on the points at issue, my own duty being not to 
undertake any extensive original study, but to merely connect their 
results together in a logical manner, to collect data for future general 
use, and to suggest, or stimulate, further inquiry on the points here 
presented. I regret that the report could not have been published 
in 1891, as many of the ideas presented therein have by delay thus 
been withheld from their practical applications to the benefit of 
agriculture. 
As the study of phenology and agriculture, in the modern spirit, 
has been cultivated for over a century in Europe, much of our knowl- 
edge must be drawn from European literature, which is really far 
too extensive to be satisfactorily summarized in the time and space 
at my disposal. Originally it was my hope to introduce into this 
report a summary of the large and sadly scattered literature of 
American phenology, including the dates of blossoming and ripening 
both of native and cultivated plants, enlarging the work already done 
in this line by F. B. Hough for the State of New York; but I did not 
succeed in completing this part of the work, and reserve it for a 
future occasion. Requests for phenological observations in the 
United States have been frequently made since 1800, and large collec- 
tions of data exist in manuscript and print sufficiently extensive to 
justify the hope that they may prove worthy of a study as elaborate 
(5) 
