It is the object of this book to lead the student to the independent discovery of the most important facts in our ordinary weather conditions, and of the interrelations of the different weather elements. This practical study having taught something as to the real nature of atmospheric phenomena by actual observation, rapid and substantial progress may be made in the knowledge of the distribution and of the explanation of similar phenomena in other parts of the world, as derived through a study of the text-books. By means of this combination of the two kinds of study, the inductive and the didactic, the advantages of both may be preserved, and the slow progress of the first method and the unsound progress of the second may be avoided. This book is not a text-book, and it therefore does not attempt to give explanations of various phenomena discovered by the class. Explanations will, of course, be called for by the scholars, in increasing number as the work progresses, and the larger relations of the study become apparent. It is best, if possible, to leave the more complicated matters (such as the cause of the deflection of the wind from the gradient, of cyclones and anticyclones, etc.) until the subjects can be taken up in detail and fully explained, for instance in the later years of the high school course. It is not advisable to raise such complicated questions in the grammar school work if they can be avoided. The teacher who has a fairly good knowledge of one comprehensive modern text-book of meteorology, such as Davis’s _Elementary Meteorology_, will find himself sufficiently well equipped to answer the questions put by the class. The value of the work outlined in this little book can be much increased if the larger applications of the lessons here learned are strongly emphasized. Suggestions along this line have been made in fine print throughout the text, but the examples given may be further extended to the great advantage of the student. Careful attention ought to be given to the formulating and writing out of the generalizations reached by the class, for in these written summaries the results are preserved in compact form. CHAPTER I. The work outlined in this chapter is adapted to the lower grades in the grammar school. It is assumed that the pupils have already had some preliminary training in the simplest non-instrumental weather observations, such as can readily be made during the primary school years. For the convenience of teachers who may desire it, a brief outline of work suited to the primary school grades is here given. It is desirable that even older scholars be given some such training as this before they take up the exercises of Chapter II.