1, 7, 8, 9, 10, 16. Meteorological Instruments. H. J. Green, 1191 Bedford Avenue, Brooklyn, N. Y. 2, 4. Instrument Shelter and Rain Gauge. _Instructions for Voluntary Observers._ United States Weather Bureau. 5. Mercurial Barometer. L. E. Knott Apparatus Co., 14 Ashburton Place, Boston, Mass. 12, 15, 53. Thermograph and Barograph Curves, and Cyclonic Composite. Davis, _Elementary Meteorology_. 17. Nephoscope. _Annals Harvard College Observatory_, Vol. XX, Part I. 48. North Atlantic Cyclone. _Pilot Chart of the North Atlantic Ocean._ United States Hydrographic Office. 51. Wind Rose. _Quarterly Journal Royal Meteorological Society_, Vol. XXIV, No. 108. INTRODUCTION. THE IMPORTANCE OF METEOROLOGY: ITS RELATIONS TO MAN. We live in the laboratory of the earth’s atmosphere. The changes from hot to cold, wet to dry, clear to cloudy, or the reverse, profoundly affect us. We make and unmake our daily plans; we study or we enjoy vacations; we vary our amusements and our clothing according to these changes. The weather forecasts for the day in the newspaper are read even before the telegraphic despatches of important events. Sailors about to put to sea govern themselves according to the storm warnings of our Weather Bureau. Farmers and shippers of fruit, meat, and vegetables anxiously watch the bulletins of cold or warm waves, and guard against damage by frost or excessive heat. Steam and electric railways prepare their snow-plows when a severe snowstorm is predicted. Meteorology, the science of the atmosphere, is thus of very great interest and importance. There is no subject a knowledge of which does more to make our daily life interesting. Since we live in the midst of the atmosphere and cannot escape from the changes that take place in it, we must, consciously or unconsciously, become observers of these changes. Examples of the varying processes at work in the atmosphere are always with us. There is no end to the number and the variety of our illustrations of these processes. Man is so profoundly affected by weather changes from day to day that all civilized countries have established weather services. Observers taking regular weather records are stationed at thousands of different places in all parts of the world, and the observations which they make are used by meteorologists in preparing daily weather maps and forecasts, and in studying the conditions of temperature, winds, and rainfall. In the United States alone there are about 3000 of these observers.