LETTER OF TRANSMITTAL. 



U. S. Department of Agriculture, 



Bureau of Plant Industry, 



Office of Chief of Bureau, 

 Washington, D. C, June 9, 1910. 

 Sir: I have the honor to transmit herewith and to recommend for 

 publication as Bulletin No. 188 of the series of this Bureau the 

 accompanying manuscript, entitled "Dry Farming in Kelation to 

 Rainfall and Evaporation," by Dr. L. J. Briggs and Mr. J. O. Belz, 

 of the Office of Physical Investigations of this Bureau. 



This manuscript has been prepared for the guidance of prospective 

 settlers in regions of limited rainfall, and contains a discussion of the 

 relation of the quantity and character of the rainfall and of the 

 evaporation to crop production under dry-farming methods in vari- 

 ous sections of the Western States. Tables showing the normal 

 rainfall for these States have also been compiled from the numerous 

 publications of the Weather Bureau, and are appended for the con- 

 venience of prospective settlers. The writers desire to express their 

 obligations to the United States Weather Bureau, and particu- 

 larly to Mr. P. C. Day, of the Climatological Division, for assistance 

 in the preparation of these tables. The illustrations, 24 in number, 

 consisting mainly of state rainfall maps, have been specially pre- 

 pared by the writers in order that the distribution of the rainfall in 

 each State may be more readily understood. 

 Respectfully, 



G. H. Powell, 

 Acting Chief of Bureau. 



Hon. James Wilson, 



Secretary of Agriculture. 



