In summer time of course the snow melts as soon as it falls into a stratum of air with a temperature above the freezing point, and continues its journey from that point as raindrops instead of snowflakes. In the formation of a snowflake Nature does some of her most beautiful work. A snowflake first forms with six ice spangles, radiating from a common center. Shorter ones form on these six spokes, standing at an angle of about sixty degrees, on each side of each spoke, of such length and arrangement as to form a symmetrical figure or flower. They do not always take the same form, but follow the same laws that govern the formation of ice crystals. The structure of a snowflake may be often found upon a window pane of a frosty morning. Here, however, the free arrangement of the parts of a snow crystal are interfered with by its contact with the window pane, but while floating gently in the air there is the utmost freedom for the play of nature's forces as they apply to the work of crystallization. The difference in structure of snowflakes is chiefly due to the conditions under which they are formed. If the moisture is frozen too rapidly the molecular forces that are active in crystallization do not have time to carry out the work, in its completeness of detail, as it will where the freezing process, as well as the condensing process, goes on more slowly. CHAPTER XVI. METEORS. Meteors are the tramps of interplanetary space. They sometimes try to steal a ride on the surface of the earth, but meet with certain destruction the moment they come within the aërial picket line of our world's defense against these wandering vagrants of the air. They have made many attempts to take this earth by storm, as it were, and many more will be made. They fire their missiles at us by the millions every year with a speed that is incredible, but thanks to the protecting influence of the great ocean of air that envelops our globe they become the victims of their own velocity.