Farmers have grumbled about the weather from time immemorial. The point of interest in this particular case is that the two grumblers do not agree about what is wrong. Farmer A thinks the corn needs rain. Farmer B declares that at this stage rain would do more harm than good. Plenty of warm sunshine is, he thinks, the right prescription to insure a “bumper” crop. Of course Providence will do as it pleases, and whatever weather comes, since it cannot be cured, must be endured; but it is a matter of practical as well as academic interest to get some inkling betimes as to how your crop is going to turn out, and the weather is likely to be the decisive factor. Moreover, it is a very significant fact that our two farmers are not of the same mind about which atmospheric blessing is in default. It is painful to reflect that an enormous amount of grumbling about the weather on the part of the rustic community must, at one time or another, have been misapplied. It is a plausible assumption that farmers have sometimes worried themselves to death over meteorological events that were either harmless or actually beneficial to their crops. How can we arrive at the facts? Admitting, as everybody does, that the weather has a preeminent influence upon plant life, is this influence susceptible of analysis? Is there anything definite about it? Are not the effects of various atmospheric conditions so entangled with one another, and with the effects of soil and methods of cultivation--to say nothing of insects and plant diseases--as to baffle all attempts to gauge them separately? There is a new branch of applied science that teaches farmers how to grumble right about the weather. It is called Agricultural Meteorology. As a coherent branch of knowledge, this subject is so new that the first formal textbook about it in the English language was published in the year 1920. It happens that the author of this book, Professor J. Warren Smith, of the United States Weather Bureau, began his investigations in the new field by making a careful study of the relation of weather to the yield of corn in Ohio. Let us see what light his studies shed upon the question at issue between our friends A and B. Day after day, and year after year, the principal atmospheric conditions are observed and measured at a great number of points scattered over the State of Ohio, as they are elsewhere throughout the Union, and the records thus obtained are carefully compiled, summed up, averaged and otherwise discussed by officials of the Weather Bureau. Thus a great fund of detailed statistical information about the weather is available for comparison with the statistics gathered by other agencies concerning the yield of crops and their condition at different stages of growth.